Electronics Australia June 1987

— Top Selling Electronics Magazine

N

Registered by Australia*Post
publication No. NBP 0240

JUNE 1987

Aust* $3.50
NZ $4.95 bse

@ Satellite TV:
what you need

@ Stereo
VU Meter

@ Local Area
Networks:
What they are,

@ Multi-channel =» What they do
remote control Simple Car
to build Burglar Alarm

i>)

The all-important high-speg@tl 0S on.
Will latch-up cause burn-

With Philips high-speed CMOS
(HCMOS) logic ICs, the answer’s
no. Because they're free from
latch-up.

What causes latch-up?

Latch-up occurs when SCRs
(formed by parasitic bipolar
transistors found in all CMOS
structures) are triggered by
current transients arising from
over-voltage at the input, output
or supply pins, or by ringing on
the signal pins. The resulting

Typical breakdown occurs at Voc = 22 V. Io = 5.5 MA.

Curve tracer display from latch-up test
with excess supply voltage. At no time
did latch-up occur in the Philips HCMOS
IC, since the supply voltage snaps back

to 13V. component

short-circuit across the supply _ C0Sts but also optimise
rails causes excessive current System speed.

inevi ; And you gain reliability. With a
pee beetle cee ee product that will not fail during

Ae system test. Or in the field. The name is Philips
How is it overcome? oe : Hcmss The product is HCMOS
We prevent any current injection — Harsh environments? er

into the SCR structures by Even in noisy, high-temperature — Want to know more? Then call
growing an epitaxial layer on a environments such as auto- your local Philips Electronic
very low-resistivity substrate. And | motive and industrial Components and Materials
by using unique design and applications, Philips HCMOS office. We're on-hand with full
process parameters to minimize | Logic goes on working. And you technical documentation,
the gain of the parasitic get exceptional noise immunity _ including a Designers Guide to
transistors, we achieved because the input switching your all-important questions
complete latch-up immunity. levels of 74HC/HCU circuits are about HOMOS.
No burn-out. 30% and 70% of the supply

So you improve system voltage. Moreover, the whole Sydney

performance, and by eliminating Philips 74HC/HCT/HCU family pe oi
additional components to protect has a standard temperature ie
against latch-up you not only cut fange from 40 to +125°C.

RCA is an alternate source for Philins HOMOS ICs.

4 railway. Details page 44.

THIS MONTH’S
COVER |

Here’s a multi-function IR
remote control that’s easy
to build and easy to install. |
Build it and press the but-
tons to control your TV |
set, CD player or model |

Features

10 NEW-GENERATION AIRLINERS Quieter and packed with electronics
16 RADAR: ITS WARTIME ROLE Recollections of an RAF instructor

26 SATELLITE TV IN AUSTRALIA A practical guide

36 TETIA AND TESA Professional organisations for the electronics technician
88 LOCAL AREA NETWORKS What they are & what they do

93 WIN A LAN DEVELOPMENT SYSTEM $10,000 prize from TI

Entertainment Electronics

104 AN INTRODUCTION TO HIFI PT.14 FM radio tuners — 2
124 COMPACT DISC REVIEWS Janos, Handel, Mozart

Projects and Technical

44 MULTI-FUNCTION REMOTE CONTROL Switch up to eight channels
60 REMOTE CONTROLLED CAR ALARM Combines two popular projects
64 CIRCUIT & DESIGN IDEAS Screecher protection for bonnet & boot
68 THE SERVICEMAN When skies are grey, Sony boy
84 LOW-COST STEREO VU METER Build it for the Mini Mixer
96 A VERSATILE OP AMP TESTER PT.2 How it’s used

112 UNDERSTANDING COLOUR TV PT.5 The colour decoder — 1

News and Comment.

4 LETTERS TO THE EDITOR For and against the Australia Card
5 EDITORIAL Australia at the forefront of superconductivity research
6 NEWS HIGHLIGHTS JBM launches new-generation PCs
38 FORUM Technology: has it gone over the top?
126 INFORMATION CENTRE Answers to reader queries

Departments

74 BOOKS REVIEWS

83 EA CROSSWORD PUZZLE

83 50 AND 25 YEARS AGO
118 NEW PRODUCTS

128 MARKETPLACE
130 COMING NEXT MONTH
NIL NOTES AND ERRATA

car burglar alarm

| Eight channel IR
| remote control

Up to eight relay channels can |

be switched with our new infra-
red remote control, and you
can add power on/off, muting
and volume control. Construc-
tion begins on page 44.

| 10,000 prize from

Texas Instruments

Do you need a local area net-
work (LAN) development sys-
tem. If so, tell us about it. You
could win a $10,000 prize from
Texas Instruments. See page 93.

Remote controlled

| This month, we show you how

to combine the UHF remote

| switch featured in January with
| the ultrasonic alarm described
in April.

Together, the two
make a very effective radio-con-
trolled car burglar alarm. De-
tails page 60.

June | |
1987,

4

MANAGING EDITOR
Leo Simpson, B.Bus. (NSWIT)

EDITOR
Greg Swain, B.Sc. (Hons. Sydney)

EDITORIAL CONSULTANT
Neville Williams, F.I.R.E.E. (Aust.)
(VK2XV)

EDITORIAL STAFF
John Clarke, B.E. (Elec. NSWIT)
Carmel Triulcio

GRAPHIC DESIGNER
Brian Jones

ART PRODUCTION
Alana Horak

PRODUCTION
Mark Moes

SECRETARIAL
Naomi Lenthen

ADVERTISING PRODUCTION
Brett Baker
Vikki Patching (Vic.)

ADVERTISING MANAGER
Selwyn Sayers

PUBLISHER
Michael Hannan

HEAD OFFICE

The Federal Publishing Company Proprietary
Limited, 180 Bourke Road, Alexandria, NSW
2015.

Phone: (02) 693 6666. Fax number: (02) 693
2842. Telex: AA74488.

Postal Address: PO Box 227, Waterloo 2017.
NSW Representative: Mark Lewis.
INTERSTATE

ADVERTISING OFFICES

Melbourne: 221a Bay Street, Port Melbourne,
Vic. 3207.

Phone: (03) 646 3111

Representative: John Oliver, B.A. (Hons.
Essex).

Adelaide: John Fairfax & Sons Ltd, 101
Weymouth Street, Adelaide, SA 5000.
Phone: (08) 212 1212.

Representative: Michael Mullin

Brisbane: 26 Chermside Street, Newstead, Qld.
4006.

Phone: (07) 854 1119.

Representative: Bernie Summers.

Perth: John Fairfax & Sons. 454 Murray Street,
Perth, WA 6000.

Phone: (09) 481 3171.

Representative: Estelle de San Miguel.

New Zealand: 3rd Floor, Communications
House, 12 Heather Street, Parnell, Auckland,
New Zealand.

Phone: (09) 39 6096. Telex: NZ 63122
SPORTBY.

Representative: John Easton
ELECTRONICS AUSTRALIA is published
monthly by the Federal Publishing
Company Pty Limited.

Typeset and printed by Hannanprint, 140
Bourke Road, Alexandria, NSW for The
Federal Publishing Company Pty Ltd.
Distributed by the Federal Publishing
Company Pty Ltd.

Registered by Australia Post — publication
No. NBP 0240.
ISSN 0313-0150

Fre

*Recommended and maximum Australian
retail price only

ELECTRONICS Australia, June 1987

Letters to
the editor

Comment on
April Editorial

Your editorial in the April copy of
Electronics Australia is a most coura-
geous stand and one that I would like to
endorse. It is high time that the people
of Australia took the trouble to look
more closely at what is being put into
our legislation, and not accept as inevi-
table that which goes on in Parliament
House.

If I may, I would like to quote a
small section of your editorial which I
feel is the most ugly aspect of this legis-
lation; ie. “There are clauses in the
legislation which would easily enable
any future totalitarian Government to
withdraw your card, which would tanta-
mount to removing your citizenship”.

This is a virtual duplicate situation to
that which prevailed when the Third
Reich came to power and quietly intro-
duced legal criteria which ultimately led
to the dehumanising of many people of
many nationalities. The scenes which
appear in the mind’s eye are horrific.

Thank you once again Mr Simpson
for your unqualified stand in bringing
this frightful evil to the notice of read-
ers of Electronics Australia.

K.E. McWilliam,

Hilltop, NSW.

In support of
the Australia card

Was the Metric Time article the only
April Fool’s joke in your last journal or
was there a second in your editorial op-
posing the Australia Card in view of the
incredible logic therein.

You state that the proposed law will
become an invasion of privacy because
“many government departments will
inevitably have access to this informa-
tion”.
credit cards and user of credit, I am
sure that many of my financial details
are held on computer files with access
given to a variety of bodies. I much
prefer the Australia Card legislation
which, by law, will establish a Data Pro-
tection Agency to the aforementioned
arrangement.

I am a subscriber to several maga-

As a holder of numerous bank :

zines, currently including yours, and I
often receive telephone calls and postal
offers from persons and organisations
who have obtained my name, address,
telephone number and interests from
these magazines. Do you sell your sub-
scription lists or are your subscriber’s
private details not divulged to anyone?

As a member and delegate of the Ad-
ministrative and Clerical Officer’s As-
sociation, I resent your bald assertion
that ACOA is “actively against” the
card, especially when our Council’s last
policy resoluton of November 1985 sup-
ported the concept of the card and
recognised the need for an adequate
and cost-effective means of implementa-
tion.

Let’s forget the trivialities to which
you refer such as ‘‘card subjects” and
concentrate on the real issue. Do we
want to support tax evaders, welfare
cheats and the like to the detriment of
honest taxpayers? The overall fairness
of the Card outweighs the negatives you
espouse.

We are not a society of individuals on
our own desert islands and as such we
have an overall responsibility — hence I
don’t for instance exercise an individu-
al’s right to drive through red _ traffic
lights. In countries such as the USA you
cannot, for example, bank money,
transfer money out of the country, or
buy a motor car over a specified price
without an identifier such as the Austra-
lia Card will become.

The Tax Office has the will to cross
match incomes with interest and. divi-
dends and when the Australia Card pro-
vides a valid identifier they can put
plans for computer purchases into real-
ity.

Your editorial has made me change
my mind but about your magazine, not
about the Australia Card. With regret I
cancel my subscription but hope that
you can either take a more responsible
stance or confine your views to the elec-
tronic interests of your readers.

I. Smillie,

Sunnybank, Qld.

Comment: Our Editorial makes the
point that the Australia Card will not

“solve the serious problems of social se-

curity fraud or tax evasion. We regret

that you have cancelled your subscrip-
tion because we have published an opin-
ion which is contrary to your own.

Nothing to do
with electronics

What has the content of your Edi-
torial in the April 1987 issue got to do
with electronics?

If I want to read political opinions
there is a host of specialised journals
etc. that cater for this purpose. I sug-
gest to you that you may write to these
publicatons as an individual as you are
sO motivated to express your opinion.

Please in future make the contents of
your Editorial more relevant to elec-
tronics and do not use your space for
politics.

V. Tantaro,

Avondale Heights, Vic.

Comment: the content of the April 1987
Editorial is relevant to an electronics
magazine. The Australia Card is a
particular application of computer tech-
nology which has far reaching social im-
plications for every Australian.

Exide Powerguard
is a no-break UPS

I fear the ‘“no-break” Exide Power-
guard UPS has been inadvertently sold
short by your otherwise excellent fea-
ture “What’s new in power supplies”
(February 1987).

This comes about by categorising the
Exide Powerguard as an “off-line
UPS”.

As you correctly stated, ‘The typical
switchover time for an off-line UPS is
under 10ms which is less than a half-
cycle duration of the 50Hz mains”’.

To demonstrate just how unlike an
off-line UPS the Exide Powerguard is,
consider that its switchover time is less
than 1ms. This is one tenth the typical
figure for an off-line UPS.

As you know, this is an important dif-
ference.

As far as a computer is concerned,
lms is undetectable from a continuous
supply of power. But anything ap-
proaching 10 milliseconds can cause
serious data corruption or loss.

The superior response of the Exide
Powerguard UPS comes about from the
fact that the mains and battery are
never really ‘off-line’? — each being
connected to its own. separate primary
of a tri-port transformer, the battery via
an inverter. The secondary of the trans-
former passes through a filter to provide

continued on page 129

-4| Editorial
f | Wiewpaint

Australia at the forefront
of research into supercon-
ductivity

Everyone will welcome the recent news that there have been real break-
throughs in research into superconductivity. Previously, superconductivity has
been thought of as a phenomenon which only occured at extremely cold tem-
peratures, close to absolute zero. It is a very important phenomenon whereby
electrical resistance in conductors drops to very low values. Discovered in
1911, there had previously been very little progress in research and interest in
this area has been very low.

Now, a number of scientists from around the world have announced that
superconductivity can be made to occur at quite ‘“‘warm” temperatures, as
high as 100 degrees Kelvin (-173 degrees Celsius). This means that no longer
is it necessary to use liquid helium as the refrigerant; liquid nitrogen can be
used instead.

It is gratifying to know that scientists at the University of NSW, Australian
National University and the CSIRO are well to the forefront of the current
research although Australia would be in a much better position if we had
more physicists who could turn their talents to this area.

The immediate effect of these breakthroughs is to rekindle interest in su-
perconductivity and already there are predictions of superconductivity being
made to occur at room temperature within 10 years. The really startling
aspect of the recent breakthroughs is that they do not involve metals as such,
but use exotic new ceramic mixtures which at normal temperatures are insula-
tors. Mind-boggling indeed!

If superconductivity does become possible at normal temperatures the
ramifications will be extreme. They could be more far-reaching than the
development of the transistor which has changed virtually every aspect of life.
Just think of the possibilities, in power generation and transmission, including
fusion, in transportation, in medicine (nuclear magnetic resonance), in com-
puters, in manufacturing and so on. If just some of these possibilities become
reality, superconductivity could effect a major reduction in world energy con-
sumption.

Really though, no-one can possibly foresee the full ramifications of super-
conductivity, just as no-one could have foreseen all the applications of the
laser 25 years after its initial development.

Leo Simpson

ELECTRONICS Australia, June 1987

5

Jaycar Electronics
opens in Melbourne

Jaycar Electronics has at last opened
a branch in Melbourne.

Situated at 45 A’Beckett St, the store
is in the heart of the Melbourne retail

electronics area. It is only a few minutes
walk from other major suppliers and
from RMIT.

The new store carries the full range
of Jaycar merchandise and is under the
management of Mr Tim Rimington. The
telephone number is (03) 663 2030.

Americans catch
“kangaroo paw’

A recent report in the US-based Co-
lumbia Journalism Review has revealed
that large numbers of American jour-
nalists are suffering from repetitive
strain injury, or RSI. The report ex-
plodes the the myth that RSI is simply a
case of “kangaroo paw” — an “imagi-
nary” injury confined strictly to Austra-
lian journalists and office workers.

In the US, the injury is commonly re-
ferred to as “‘computeritis” or ‘“com-
puter complaint”. According to the re-
port, serious and disabling arm and
hand disorders have afflicted employees
using video display terminals at newspa-
pers across the country, including the
San Francisco Chronicle and Examiner,
Newsday, the New York Daily News,

Business Briefs

the Los Angeles Times, The Philadel-
phia Inquirer and the San Diego Trib-
une.

As in Australia, American newsrooms
rely extensively on VDT equipment.
But why does the problem arise with
computer keyboards and not with the
now outdated manual typewriters? One
answer. say occupational health special-
ists, is that although some typists do de-
velop such injuries, VDT users may be
at greater risk because they can make
many more hand movements per hour.

Another factor that may contribute to
injuries is that reporters are simply
using their VDTs more than they used
typewriters. Preliminary studies have
shown that users are more likely to suf-
fer RSI if they work on the computer
for long periods of time, concentrating
very hard, and rarely taking breaks.

® Rifa Pty Ltd has expanded its operations in Preston, Victoria.

In addition to extra office space, Rifa has included a new trade counter
which is intended to supply all the electronic component needs of
tradesmen and professional hobbyists.

@ Allen-Bradley Pty Ltd has announced new distributors in South Aus-

tralia and for the first time in the ACT.

The new contact in South Australia is Electronic Components and
Equipment Pty Ltd, 30-40 Hurtle Square, Adelaide. Telephone Arthur

Watson on (08) 232 0001.

The distributor in the ACT is Electronic Components Pty Ltd, PO Box
534, Fyswick 2609. Telephone (062) 80 4654.

6 ELECTRONICS Australia, June 1987

Philips exports a parrot
- but it’s legal

A TV commercial produced for
Philips Australia, and starring a parrot,
should bring some some extra colour to
Morocco.

Rick’s Cafe Americain must be the
most famous location in Morocco. Mil-
lions of moviegoers and TV viewers can
describe the decor of the fictitious
Rick’s Cafe but only in the black and
white details of the 1942 Bogart-Berg-
man classic Casablanca.

Yet Morocco does have colour —
since 1977 in fact, when colour televi-
sion was introduced to this north-west

NSW Innovation centre

As from the Ist May, 1987 the Inno-
vation Centre of NSW will manage a
service which will enable creators of
new products, processes and materials
to quickly reach manufacturers, inves-
tors and entrepreneurs.

It is the only such scheme in Austra-
lia and is expected to be one of several
services that will help to generate a
growing private manufacturing sector
which is responsive to the needs of local
and overseas markets.

A major problem faced by product
developers is that they cannot readily
present their products to appropriate
manufacturers, investors or marketers.
At the same time, the Centre is often
approached by manufacturing compa-
nies looking for new products.

By registering with the AISS (Austra-
lian Innovation Sourcing Service), both
parties can be brought together. The In-
novation Centre also provides other ser-
vices to members, such as help with
business planning and marketing advice.

The Australian Innovation Centres
are supported by Federal and State
Governments, as well as industry
groups. Enquiries can be directed to the
Innovation Centre of NSW, PO Box 1,
Kensington, NSW 2033. Telephone (02)
399 6111.

African nation’s population. One third
of the 1.1 million homes now own co-
lour a TV set and annual sales are
about 100,000 sets.

So what’s that got to do with the par-
rot? Well, Philips has proved to be the
most popular brand of colour television
in Morocco and marketing executives
intend to keep it that way by pushing
the ‘Natural Colour’ theme that is so
well known to Australian viewers.

To promote this theme, the 1987 ad-
vertising campaign will include a com-
mercial that was originally made in Aus-
tralia in 1985. This advertisement fea-
tures an artist painting onto canvas the
details of a live parrot she is studying
on a Philips screen.The commercial was
judged by Philips executives in Morocco
to have been the best TV spot on a reel
of Philips commercials made around the
world in the last few years.

Of course, there will be a few produc-
tion costs. First, the video signal will
have to be converted from the PAL sys-
tem, as used in Australia, to Morocco’s
SECAM system. In addition, the narra-
tive will be translated into French, while
the sound effect will be repeated — par-
rot fashion of course.

Spaceplane contract

British Aerospace Australia and the
University of Queensland have won a
contract from the Australian Govern-
ment to study the feasibility of develop-
ing a Re-Entry Air Data System
(READS) for space vehicles re-entering
the Earth’s atmosphere.

Conventional aircraft calculate their
air speed by measuring the pressure in-
side tubes (‘‘pitot” tubes) protruding
into the airstream. At hypersonic speeds
high in the atmosphere, these tubes
would be burnt off.

The research is applicable to a num-
ber of advanced projects — HOTOL in
Britain, Hermes in France and Amer-
ica’s National Aerospaceplane. Results
could also be used to upgrade systems
already in use on NASA’s space shuttle.

Engineers from British Aerospace
Australia and the University of Queens-
land will be conducting their studies in
Europe and the United States. The Hy-
personic Shock Tube facility at Queens-
land will be used in the early design
stages of these projects.

British Aerospace Australia’s other
space-related contracts include the de-
sign of the Earth Resources Satellite
ground system and the Queensland
Government space launch site study.

- Jan Graham, UK.

a

Plessey’s working
on the railroad

Communications within the State Rail
Authority will be substantially upgraded
following the installation of a $5 million
Plessey dial-upradio telephone network.

Details of the system, which puts
maintenance and emergency personnel
in immediate contact with any SRA
telephone extension throughout the
coverage area, were announced on
April 10th during a visit to Plessey’s
Meadowbank Sydney plant by the NSW
Deputy Prenier and Minister for Trans-
port, Mr Ron Mulock.

Designed and manufactured by Ples-
sey in Australia, the SRA system in-
cludes more than 1000 Plessey
MTR8000 Series UHF vehicle and per-
sonnel transceivers, nine base station
sites, and a network management centre

at the State Rail Authority’s Chullora
depot.

All sites are interconnected by micro-
wave radio links which were also sup-
plied by Plessey.

An area from Helensburgh south of
the Sydney metropolitan area to Wyong
on the NSW Central Coast is covered
by the new dial-up network, with the
system design also catering for future
extension to Wollongong and Newcas-
tle.

Plessey has substantially upgraded its
Meadowbank facility in recent years.
The company is now successfully in-
volved in a number of new technology
fields ranging from B-MAC satellite TV
systems to the Raven field radio system
for the Army. The latter is said to be
the most advanced battlefield radio sys-
tem in the world and has definite export
potential.

ELECTRONICS Australia, June 1987 7

News Highlights

Robots on patrol

Sam Technology of Marayong, Aus-
tralia is now distributing an impressive
new surveillance robot which can do
many of the things that a human guard
can do.

Called the Sentry, the new robot
resembles R2D2 from Star Wars. It
weighs 220kg, stands 120cm tall, and is
ideal for firms that do not like the idea
of anyone — not even security people
— roaming free to peruse confidential
material.

Once led through its route, the Sentry
robot creates in its memory banks a
map which it uses to continue its patrol
at up to 6km/h for 12 hours at a stretch
before its on-board power supply run
low. The robot then seeks out its own
“sentry box” for recharging.

The new robot comes with an impres-
sive array of electronic sensors, includ-
ing 24 ultrasonic sensors around its cir-
cumference which detect objects in its
path. Also featured are infrared sensors
which are able to detect fire or body
heat.

In addition, the robot has a miniature
video camera through which it can send
back to a central security room a pic-
ture of what is happening as it on pa-
trol. If the Sentry detects trouble, it
sends a silent alarm to either the central
security station or to the proper authori-
ties.

Government abandons
ABC/SBS merger plan

The proposed merger of the SBS
(Special Broadcasting Service) with the
ABC has been abandoned by the Fed-
eral Government.

The announcement was made by the
Prime Minister, Mr Hawke during a re-
cent address in Melbourne.

The controversial merger was first an-
nounced in the 1986 Budget but the
legislation was blocked by the Senate
last December. This rejection meant
that SBS were prevented from receiving
any benefits by the Government.

Mr Hawke’s decision not to proceed
has pre-empted any recommendation to
the Senate Select Committee which has
been hearing submissions on the pros
and cons of the merger.

8 ELECTRONICS Australia, June 1987

With optional attachments, the Sentry
is expected to find applications for han-
dling hazardous waste and explosive. At
present the US Army is investigating
military implications.

And the price of all this electronic
wizardry? — around $160,000. (Sam
Technology, 36 Binney Rd, Marayong,
NSW 2148).

New electronics course
at Footscray TAFE

A new syllabus to train technical offi-
cers and engineers’ assistants in Com-
puter Integrated Manufacturing (CIM)
has been developed at Footscray Col-
lege of TAFE. The course will lead to a
new qualification: the Certificate of
Technology (Electronics — CIM).

Following accreditation by the Victo-
rian TAFE Board, the syllabus is likely
to be introduced Victoria-wide and pos-
sibly nationally. It will lead to a new
qualification — the Certificate of Tech-
nology (Electronics — CIM).

One of the developers of the course,
Footscray College’s Bill Green, says
that while the use of high technology in
Australia has advanced rapidly, training
for technicians and technial officers in
the electronics industry has lagged be-
hind.

Mr Green, who developed the sylla-
bus with fellow Footscray College staff
member Bert Leckie, and Keith Robin-
son of RMIT, says that they initiated
the project about three years ago. Also
involved at every stage was an industry
panel which included Don Bryant of the
Government Aircraft Factory; Paul
Dunn, Division of Manufacturing Tech-
nology, CSIRO; Dan Lambert, L.M.
Erricsson Pty Ltd; Don Sheridon, Tele-
com Research Laboratories; and Ray
Smith, RCS Design Pty Ltd.

For further information contact Bill
Green, Footscray College of TAFE,
Cnr Nicholson & Buckley Sts, Foot-
scray, Vic. 3011. Phone 688 3400.

Superconducting chips a possibility says IBM

Researchers at the IBM Thomas J.
Watson Research Centre (Yorktown
Heights, NY, USA) have announced a
major breakthrough in the development
of the first thin-film superconducting de-
vices that operate at temperatures high
enough to be of practical use.

IBM’s ability to make such devices
opens the door to producing instru-
ments and chips that are the supercon-
ducting counterparts to those used in
computers and other electronic prod-
ucts. A superconductor is a material
that loses all resistance to electricty
below a specific “transition” tempera-
ture.

The new IBM devices, called
SQUIDS (Superconducting Quantum
Interference Devices), are the most

sensitive magnetic detectors known to
science. Composed of two thin-film Jo-
sephson devices each, the SQUIDS are
only one one-hundredth the thickness of
a human hair and are superconducting
at up to 68 degrees Kelvin (K) (minus
337 degrees Fahrenheit).

These new SQUIDS become com-
pletely superconducting in the range
where liquid nitrogen can be used as the
coolant. Liquid nitrogen boils at 77 de-
grees K and can be effectively employed
at 68 degrees K by reducing its pres-
sure.

Liquid nitrogen is much less expen-
sive and more convenient than the
liquid helium used in current supercon-
ductivity applications.

Only

from...

n tne thirt

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Obviously, we've given our store managers guidelines. But to be classed as a
regular customer is easy — if you're a regular customer!

omers: You don’

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ler expire

PTY LTD

Quieter, fuel efficie

Airbus Industrie’s A300 fly-by-wire demonstrator goes through its impressive flying
display at the 1986 Farnborough Air Show. (Photo: British Aerospace).

isin 308

i

eS Gog
8S Bed

HEB OB

‘ is OE RT
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ferbiae®
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Computer text and graphics present information about the
strumentation.

10

“BRAKE
aircraft to the crew in a clearer and more flexible way than conventional in-

ELECTRONICS Australia, June 1987

and packed with electronics

we
New-generation
® ] ©
It is not an exaggeration to say that
electronics is revolutionising aviation. Of
course, most of the leading edge research is

devoted to military aircraft but civil aircraft,
too, are experiencing rapid advancements.

by IAN GRAHAM

As you board your aircraft in ten
years time, will it be a sleek supersonic
dart? Probably: not. It’s more likely to
be a subsonic aircraft with propellers
(yes, propellers!) and a remarkable new
control system.

Within ten years, aircraft will begin to
lose the familiar control column that has
been a feature of the flight deck since
the first planes took to the air at the
beginning of the century. The control
column, or ‘‘joystick”, is designed and
built the way it is because the pilot
needs the extra leverage of the column
height to help him physically pull the
plane’s control surfaces (rudder, tail-
plane, etc) into position.

The column is linked to the control
surfaces by a network of cables, pulleys
and other mechanical and_ hydraulic
linkages. But that arrangement will cer-
tainly change dramatically as a result of
implementing a system called “fly-by-
wire” that has already been used by
military plane-makers for the past dec-
ade.

To survive in the air, modern fighters
‘have to be very nimble indeed. Very
stable aircraft — aircraft that will return
to straight, level flight if the pilot takes
his hands off the controls — tend to
very sluggish to manoeuvre, because
they’re always trying to return to their
stable attitude. Aircraft designed for

aerobatic displays achieve increased ma-
noeuvrability by having a degree of in-
built instability. The less stable they
are, the more quickly and easily they
respond to the controls, because they’re
not continually trying to return to stable
flight.

Fighter aircraft use this reduction of
stability for increased agility. But there
comes a point where the plane can be
made so unstable that a human pilot
cannot possibly fly it. But a computer
can.

Computer control

A computer can monitor the plane’s
attitude perhaps 50 times a second and
apply tiny adjustments to maintain good
trim. The computer sits between the
pilot and his plane. The pilot moves the
controls, but all he is doing is signalling
the computer what he wants the plane
to do. It is the computer that decides
how best to do what the pilot wants.

This engine, developed in America by General Electric and NASA, is the forerunner of
the new generation of ‘propfan’ or ‘unducted fan’ aircraft engines. (Photo: General Elec-
tric).

ELECTRONICS Australia, June 1987 11

Aerospace).

Planes like British Aerospace’s EAP
(Experimental Aircraft Program) and
the French Dassault-Breguet Rafale,
forerunners of the next generation of
European fighters, could not fly without
this “fly-by-wire” technology.

Compared to modern fighter aircraft,
civil airliners are aerodynamically very
stable indeed. Some designers plan to
incorporate fly-by-wire into the next
generation of civil airliners for a differ-
ent reason. At the last Farnborough Air
Show in September last year, Airbus In-
dustrie demonstrated an A300 Airbus
with a difference.

In a very impressive demonstration of
the capabilities of fly-by-wire, the pilot
flew the A300 along the runway very
low, very slow and with its nose pitched
up. It was dangerously close to the
point where it would stall and fall out of
the sky.

An aircraft of that size would nor-
mally need several hundred feet of
space underneath it to recover from a
stall. If this aircraft had stalled, it would
certainly have had a close (and expen-
sive) encounter with the runway. But
whether the pilot had inadvertently al-
lowed his plane to reach the beginning

12 ELECTRONICS Australia, June 1987

In this mock-up of a future cockpit, computer generated images on cathode ray tubes replace conventional needle

of a stall or deliberately decided to fly it
into the ground, the plane would not
have done so!

This plane was equipped with fly-by-
wire. Its computer could sense condi-
tions like an imminent stall, ground
proximity or wind shear (potentially le-
thal wind conditons near the ground
that can cut the lift from an aircraft as it
comes in to land). If the computer sys-
tem detected a dangerous situation, it
could take over control of the aircraft
and fly it to safety.

As if to drive this point home, the
pilot flew the plane slowly along the
runway and then pulled the stick back.
Any normal aircraft would have stalled,
but the computer system automatically
brought up the engine power and modi-
fied the nose-up attitude so that the
plane could climb away from the ground
safely.

Fly-by-wire promises to make a posi-
tive contribution to air safety. Of
course, it’s advantages are all lost if the
system fails or if all channels of the sys-
tem suffer from an identical fault. The
designers have naturally given all the
systems back-ups. For example, there
are at least four power generation sys-

ae

gauges. (Phote: British

tems, driven from a number of different
power plants. If one fails, another trips
in automatically.

Primary systems and their back-ups
are not only run by different computer
programs, but the hardware in the pri-
mary systems and their back-ups is also
different. Different companies supply
different computers, using different mi-
croprocessors to guarantee that the
same fault cannot possibly exist in more
than one channel of the system. Cables
are run along different routes, so that
minor physical damage to the aircraft
should not knock out any more than
one channel.

But what if all the electronics do fail?
Just as computers occasionally issue gas
bills for millions of pounds or signal the
Pentagon that World War Three is im-
minent, aircraft systems aren’t perfect
and never will be. If the Airbus loses all
electrical power from its control system,
an emergency mechanical system can be
engaged, giving the crew just enough
control to fly the plane.

As the crew is normally only sending
electrical signals to a computer system,
the control column can be dispensed
with altogether and be replaced by a

tiny hand controller reeassembling a
computer games joystick.

Of course, the move away from “‘nee-
dle and dial” instruments to multi-pur-
pose cathode ray tubes (television
screens) linked to computerised flight
management systems has already begun
and the Airbus was also “instrumental”
in implementing this leap in technology.
The trend now, with the computerisa-
tion of more and more systems on the
aircraft, is to gradually integrate these
individual systems into one super-sys-
tem.

Back to propellers

As aircraft become increasingly com-
puterised “space-age” machines, why
should propellers be making a come-
back? They’re old hat, aren’t they?
They disappeared from large passenger
aircraft in the 1960s when suitable jet
engines were developed. Twenty years
ago, fuel was a fraction of today’s prices
and so it made sense to move away

from noisy propellers to quieter (inside
the passenger cabin) and faster jet
power. .

Now, though, fuel economy is a criti-
cal factor in airline economics and de-
signers are looking again at the more
fuel-efficient propeller. The high speed
designs have curious curling swept-back
blades. The first experimental “prop-
fan” engines (also called UnDucted
Fans or UDF) have been run up to
speed on test beds and in flying trials
and appear to be capable of the same
order of power outputs as current jet
engines.

New materials and improved control
of the propeller blades by a technique
called synchrophasing all help to reduce
this propeller’s noise problem. Inside
the cabin, wall panels may be vibrated
like flat loudspeakers out of phase with
the engine vibrations in order to “can-
cel” them out and dramatically reduce
the noise and vibration levels experi-
enced by passengers. This technique is

also known as active anti-sound.

Boeing has already enlisted the sup-
port of several Japanese aerospace com-
panies to build a new aircraft, code-
named the 7J7, which will be powered
by prop-fans. The 7J7 is expected to fly
in 1991 and to enter service in the
world’s airways in 1992. McDonnel-
Douglas has also unveilled plans to
build a prop-fan-powered aircraft, code-
named the MD-91X. All the major en-
gine and aircraft manufacturers are in-
volved in the development of prop-fan
engines and the aircraft that will carry
them, so propellers are certain to reap-
pear in the 1990s.

So, the plane that whisks you off for
your holidays in the 1990s will probably
have exotic curling, swept-back propel-
lers. It will also have a “Buck Rogers”
flight deck bristling with computer
screens and hand controllers, be eerily
quiet inside the cabin, and will actually
be flown by a computer system “‘man-
aged” and supervised by the aircrew. @

*

British Aerospace’s Experimental Aircraft Program (EAP) technology demonstrator — a flying test bed for the military aircraft of the fu-

ture. (Photo: British Aerospace).

ELECTRONICS Australia, June 1987 13

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Radar;
its f§
wartime |
role;:: — |

Radar played a GR@CiaTOle i the Outcome OF :
the Second Worlc¥giepeere: die_cCior
reflects on some ON##@ Gevelooments tat

took place during hiStgee¥ears as aecnmca:

instructor with the Royal AgaGree:

by DOUG THWALBES

During the last war many new ideas
emerged and were rapidly developed.
Of these, radar was one of the most sig-
nificant.

Early in 1940, I entered the RAF and
joined a group of technicians who were
called ‘‘Radio Mechanics” but who
would never touch a radio. It was radar
we were going to service but it was
called “RDF” (Radio Direction Find-
ing) in those days.

After a quick course in VHF tech-
niques, we got an introduction to the
first airborne equipment. We were then
split up and sent to different areas. I
was sent to the east coast of Scotland.
The flying activities in this area involved
patrolling the sea and coast of occupied
Denmark and Norway.

The RDF sets used for this purpose
were called “ASV” (Aircraft to Surface
Vessel) and the first ones were a mix-
ture. The receiver was, in fact, part of a
commercial TV, but the transmitter was
made for the job.

Two transmitting valves with quarter
wave stubs as the anode circuit, and
working as a blocking oscillator, sent
out pulses of radiation at VHF. The re- Centimetric AI (Aircraft Interception): this dish with dipole antenna produced a torch-
flected signal, after passing through the _ like beam and scanned in a spiral from dead ahead outward to the circumference and
receiver, was displayed on the vertical then in a decreasing spiral back to the centre again.

16 ELECTRONICS Australia, June 1987

trace of a small CRT. This trace was
started by the transmitter pulse, so the
distancé up the trace was related to the
distance of the object from the aircraft.
The target direction was determined by
two stub antennas, mounted one either
side of the aircraft’s nose, which were
switched in synchronism with the re-
ceiver output. The output from the left
antenna deflected the trace to the left,
and vice versa.

At the same time, it was important
that ground stations could identify
friend from foe and so IFF was born.
When IFF received an RDF pulse, it
transmitted a series of pulses that .pro-
duced a recognisable effect at the
ground station.

The trouble with these devices was
that they were fitted with an explosive
charge detonated by a gravity switch on
the nose of the aircraft. The idea of this
was that it would go off when the air-
craft crashed, but it could also be
. tripped accidentally if someone knocked
the switch with a ladder when working
on the motors.

One of our jobs was to connect the
plug to the detonator, prior to take off.
Just think of the shock if, in the middle
of the night, you put the plug in and it
blew up. And they did, but luckily not
on me.

We also had a Beacon to guide air-
craft home. It was an IFF but coded to
identify our aerodrome. ASV had its
drawbacks of course, one being that it
was a forward seeking device. this
meant that ships or submarines on the
surface could be missed if they were
some way to either side of the aircraft’s
track.

To overcome this problem, phased ar-
rays were fitted to some aircraft behind
the wings. This gave a narrow beam to
either side of the aircraft.

Night fighters

Night fighters used an RDF system
but it was called AI (Aircraft Intercep-
tion). The ground RDF stations could
determine the number of enemy aircraft
approaching the coast, and their height,
distance and bearing. By this means,
ground controllers were able to direct
the fighters to the “Bandits”, with IFF
sorting out who was who.

By 1941, I had joined Technical
Training Command and was training
aircrew in the use of ASV as a method
of navigating as well as detecting sur-
face vessels. This entailed in-flight train-
ing in a blacked out cabin, flying six
hours a day six days a week at Prest-
wick, on the west coast of Scotland.

As the ‘situation in Europe had de-

A Lincoln bomber showing the blister shielding the H2S scanner directly under the gun
turret.

H2S scanner with blister removed, showing the dish that is fed by a slotted waveguide an-

tenna array.

teriorated, half of the school staff were
sent to Canada to start a similar school
there, “just in case”. By now we had
better equipment as the country had
geared up for war, and radar was in full
production.

As technicians were required in large
numbers to service this new equipment,
hundreds of personnel had been training
for the past year in different schools as
electronic technicians. I was moved to
London where a radar school had been
set up in the Royal School of Arts
building in South Kensington, ready to
give them their training in the new
radar that would soon be fitted to thou-
sands of bombers for the mass raids on
Germany. I went to Malvern University
to find out what this new radar would
do.

The Magnetron

With the development of the Magne-
tron the whole radar scene had
changed, as by using centimetric wave-
lengths very narrow beams could be

achieved without hugh cumbersome ar-
rays.

Just like a torch, a dish antenna could
focus the energy into a narrow beam.
The new radar was called “H2S”, and
worked on a wavelength of 10 centime-
tres. It used a beam that rotated and
covered a large circle, the middle of
which lay directly under the aircraft.
The beam had to be wide in the vertical
direction and very narrow in the hori-
zontal to get good definition of objects.

This was achieved by using a portion
of a dish which was narrow in height to
give a narrow beam, and feeding the
wide section with a slotted waveguide
antenna.

However, to have this dish scanner
stuck in the slipstream would affect the
aircraft’s flying performance so it was
fitted inside a streamlined blister on the
underside of the fuselage.

The display method was new, using
two CRTs mounted one above the
other. The upper one had an electro-
magnetic winding (yoke) which rotated

ELECTRONICS Australia, June 1987 17

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The other CRTs are for navigation systems.

around the neck and produced a trace
that started in the middle of the tube
face and travelled to the circumference.
This rotation was synchronised with the
antenna rotation and, each time the an-
tenna faced ahead, the trace was illumi-
nated.

This produced a radar map of the
area over which the plane was flying,
and the bright trace was the aircraft’s
course. Bright-up pulses were fed to the
tube at set intervals to. give the range
rings. We now had a method of flying
over sea or land at night and navigating
with this aid, but more was needed to
bomb with accuracy.

To hit a target with a bomb, the dis-
tance from the target to the point on
the ground directly under the aircraft
had to be determined. This was done
using the radar to measure the height
(one side) and the distance from the
plane to the target (hypotenuse). It was
then a simple matter of using Pythago-
ras’s Theorem to determine the distance
to the target from the point on the
ground directly beneath the aircraft.

How it was done was almost equally
as simple. Under the PPI (plan position
indicator) display was a small tube with
a normal vertical trace, on which the
first visible echo was that of the land
underneath.

The distance of this echo up the trace
was of course the height. A pulse with a
variable delay was used to measure this.
Another variable delay produced a
range ring that could be set on the se-
lected target on the PPI. The two con-
trols were in a small box with interact-
ing controls and a scale from which the

sities.

HS equipment in a Lincoln bomber. The transmitter is to the right of the display unit. |

,gound range could be read.

This new equipment was called H2S
from the Theorem. So H2 is the height
squared (one side) and S is the slant
range from aircraft to target (hypote-
nuse). To make this system even more
effective, an aerial photo of the target
area was obtained, and from this a
three dimensional reproduction of the
target was constructed on a sheet of
glass.

This was submerged in a tank of
water and scanned by a beam of ultra-
sound from a rotating transducer just
beneath the surface. The transducer it-
self was driven by a motor synchronised
with a PPI yoke. By this means, it was
possible to produce a simulated radar
picture.

This was photographed and copies
used to make it easier for the radar
operator to identify the target. The H2S
equipment was fitted to Mosquito
“pathfinder” aircraft which would locate
the target and identify it by the use of
pyrotechnical bombs. These created
large coloured flares that could be seen
by the bomber streams approching the
area.

Maritime radar

H2S ASV was also used in the war
against the submarine. An unexpected
benefit was the ability to detect wind di-
‘rection at sea level. It was soon discov-
ered that the sea return at the centre of
the PPI was elongated in the direction
of the wind source. This was because
the pulses were relected more strongly
from the back of a wave than from the
sloping front.

As pulse technology developed, use
was made of strobe pulses to lock on to
echos and stay with them. A stobe pulse
was placed on an echo, and then only
that signal was allowed through a gating
circuit. Two strobe pulses were then
used to gate both the leading half of the
signal and the trailing half.

The two signals were compared and,
as the range decreased, the leading half
would become longer. This, in turn,
would cause the delay producing the
strobe pulses to change until the signals
were once again equal. Thus, a target’s
range from the aircraft was now pro-
duced as an electronic value.

This information was used to develop
an ASV that would release depth
charges at exactly the right time with
deadly accuracy. Now all a pilot had to
do was lock the strobe onto a selected
echo on his PPI and then fly with that
echo on his illuminated course trace.
The equipment even opened the bomb
doors for him.

As submarines in those days had to
surface every night to recharge their
batteries, they were sitting ducks for
this euqipment. However, initial enthu-
siasm was lowered after the rumoured
sinking of some Spanish fishing boats
one night. But constant research was
taking place and radar equipment work-
ing at 3cm and then 1.25cm was pro-
duced. These gave more detailed pic-
tures but had much higher losses in
cloud or rain.

As D-Day approached it was essential
that all enemy coastal radars be put out
of action. The ‘“‘boffins” loved fancy
names and “Wire Basket” was no ex-
ception. This device scanned the radar
bands and marked any received signals
on a roll of paper.

The position of the marks would give
the frequency and a scale on the paper
edge gave the time. If fitted to an air-
craft that then flew a predetermined
course at a set speed, information
would be recorded on all radar sites in
the area covered.

A team of trained airwomen ex-
tracted from these rolls of paper the
exact position of every radar site along
the French coast, and mass bomber
raids made sure that they were not
working when the Allied invasion fleet
crossed the channel.

Since the end of that war, military
radar has become so sophisticated that
the wartime radar now seems primitive.
But, primitive or not, it played a crucial
role in many theatres of conflict and set
the stage for rapid post-war develop-
ment.. @

ELECTRONICS Australia, June 1987 19

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4001 50 74154 2.75 3.95 745475 9.90 NES58 5101 7799 | -8C640 ‘50 2N2219 28J56 17.50
4002 50 74155 1.20 3.95 74$482 11.90 NES560 8101 790 BCY70 1.90 2N2222A 2SK134 7.95
4006 1.90 74161 1.20 6.75 748489 7.90 NES67 2532 «1250 BCY71 1.90 2N2369 2SK176 17.50
4007 40 74163 1.40 6.50 NE570 27256 «11.50 + 8D139 60 —-2N2484
4008 1.20, 74164 1.20 2.20 000 sxRIES NES71 27512 29.50 8D140 60 2N2646 5 DIODES
4010 90 74165 1.20 2.20 8035 6.90 NES92 6.90 41256 5.95 8D232 ‘90 2N2647 5 1N4002 15
4011 40 © 74166 =—*1.70 220 8039 7.90 NE594 9.50 BD233 90 2N2894 1. 1N4007 20
4012 40 74174 1.45 2.20 8080 6.00 LM709-14 150 opro BD235 90 2N2904 1.10 1N414B 0.10
4013 60 = 74175 1.20 2.20 8085 9.50 UATIOCN 1.00 4N25 1.50 8D236 90 2N2905 1.10 1N5404 30 7
4014 1.90 74180 1.20 3.95 8086 19.50 LM711 1.20 4nz6 150 80237 90 2N2006 1.10 1N5408 = .40
4015 1.90 74190 = 1.00 1.00 8088 = 19.50 LM723 ‘75 4N27 150 8D238 90 2N2907 1.10 OA47 80
4016 1.00 74191 1.45 1.00 8121 5.00 LM723CH 1.50 4N28 1.50 8D262 1.20 2N3019 1.90 OA90 40
4017 1.50 74192 1.65 1.00 8123 4.00 LM725 4.75 N29 150 80263 1.20 2N3053 90 OA95 40
4018 1.90 74193 80 1.00 8130 6.95 M733 1.50 4N30 2:00 BD437 1.50 = 2N3054 «1.90 5082-2800 2.95 8087 CHI PS ]
4019 90 74194 1.10 1.90 8131 5.95 LM739 2.75 4N32 250 BD488 1.50 2N3055 1.20 5082-2811 4.95
4020 1.50 74195 1.00 1.90 8136 6.95 LM741 60 4N33 250 D647 1.80 13096 1.20 HLMP6620 5.95
4021 1.50 74197 1.10 1.00 8155 6.50 UAT47 1.30 4N35 250 8D648 1.80 2N3109 1.90 from $279
4022 1,50 74221 1.90 2.15 8156 11.50 -UA748 1.00 4N37 250 80677 1.80 2N3251 1.90
se ie i ig 1 Hts “G2 MEIN? $2 ete, Fe ame, 2 eI IH 279
i z 4 B1LS95 3.75 1312 7. . E EB
mens Hey cele, a8 100 giLS86 3.75 McIaI4 7.95 Merge: eae BOVEAB 550 NSEd] 290 Wo2 9 8087-3 (4.77MHz) $27:
75110 . 1 B1LS97 3.75 MC1315 8.95 ¢ : . c
4027 1.50 75150 2.50 1.80 g1LS98 3.75 MC1327 7.95 itera Head BDX63 6.50 2N3563 30 6AMP 8087-2 (8MH2).... $399
4028 150 75154 2.50 2.00 a2i2 2.90 MC1350 1.95 ENDso7 200 Y96 (BUX 80) 2N3564 = «30S BPC602_ 2.90
4029 150 75450 1.50 250 9214 4.90 MC140aL8 7:50 FNDSO7 2.00 4.90 2N3565 130 KBPC604 3.50 8087-1 a OMHz). . $649
4030 1.50 75451 90 3.00 224 3.50 MC1437 4.95 TiLgiaq 2.95 BDY97(BUX80) 2N3566 30 KBPC608 4.50
4031 2.95 75452 90 1.90 8226 490 MC1445 5.95 TIL306 22.50. 4.90 2N3567 30 10AMP 80287-3 (6MHz) $499
4032 2.75 75453 :90 5.50 9228 5.50 MC1456 1.95 wAN72(DL702) BFI15 1.50 2N3568 «= 30. KBPC 1002 4.20 “
4033 2.75 75461 1.50 5.50 9237 19.50 MC1458_—_1.20 702) BFi80 1.20 2N3569 «= 30S KBPC1004 4.90 80287-7 8MHz) $699
4034 3.50 75462 1.50 d 5.50 8238 9.50 MC1466L 21.50 MAN74 (DL 704) BF182 90 2N3638 30° 35AMP a
4035 1.95 75471 3.00 ‘ 5.50 9243 8.50 MC1469R 6.90 BF183 60 2N3640 30 KBPC3502 5.90 77MH 279
4038 = «3.25 75472 3.00 ‘ 5.50 6251 6.90 MC1488 1:20 gpwso ssc «BF184. «= 60, -2N3641. «(30 KBPC35014MD 8087-3 (4.77 Z)
4040 1.20 75491 2.00 60 2.20 8253 7.50 MC1489 1.20 cays9a 1.95 BF198 60 2N3642 30. A3504_—s«6.90
4041 1.50 75492 2.00 ; 5.50 9255 550 MC1494 840 Hpsoge-- 214 BF199 60 2N3643. 30 © KBPC3510 MDA
oe 1 00 75493 3.00 é i iad 8257 16.50 MC1495 9.90 4.95 BF200 120 aNsess 30 3510 9.90
: : : 8259 6.50 MC1496 2. f :
4044 1:20 7a i 5.50 8272 33.00 LM1596 3.00 FIEMP66203.95 Beas 1'5y | ON3646 «30 von race S$PO256A-AL2
ie 38 Hee igs 22 HR MAES (BE dm ceo a Bret 18 RE TR aon
sp 74C02 A a 5.9) 8274 42.50 LM1812 10.50 ‘ hf
4047 1.20 74C04 =~ *1.20 f 3.95 8275 38.50 Lwigz0 "3.90 gmm YELL 30 BF459 © «1.00 -2N3739. «4.50 7805KC 2.50 SPEECH CHIP
4048 1.20 74C08 1.00 e 2.75 8276 28.50 M2907 3.90 5mm RED .15 BF469 1.20 2N3771 5.50 7812UC 1.20 Ss h synthesiser chip, needs
4049 1.00 74C10 1.00 fi 2.75 8279 8.50 [M2917 8 PIN 3mm YELL 30 BF470 1.20 2N3772 5.70 7812KC 2.50 peech sy! iP;
4050 1.00 74014 1.75 4 5.95 8282 6.90 4.90 mm GRN 30 8F494 90 2N3773. 5.90 7815UC 1.20 programming to work.
4051 150 74C20 ~—-1.00 4 5.95 283 6.50 LM291714PIN Smm ORA 30 BFW10 1.50 2N3792 6.00 7815KC 2.50 1-9 10+ 100+
#313 HER 88 rr re a
4 E 7403211 { 2.75 8286 6.50 MN3001 17.50 : i i $ $
4084 390 74C42 2.25 k 275 9287 650 CA3028 200 GEN RECT 30 BFYSO 120 -2N3904. «1.00 7824UC_ 1.20 $1 5.00 $14.50 $14.00
4055 3.90 74048 2.95 : 2.75 8289 73.00 CA3046 1.99 RED CHROME BFY90 1.90 2N3906 1.00 7824KC 2.50
4056 4.20 74073 1.75 : 2.75 82823 5.95 CA3056 650 BEZEL 1.20 BUI26 2.95 2N4030 1.50 7905UC 1.90
i 58 Me 38 a a a
. 74C76 . 4 1.75 9303 5.50 CA3080 1.90 x . é
4066 250 74C83 5.95 ‘ 2.75 8304 6.95 CA3086 190 CHME BEZE' BUX80 4.90 2N4036 2.50 7912KC 250 Cc | $256-AL2
4067 9.90 74C85 5.95 ‘ 2.55 8311 5.95 CA3100E 7.95 GRAN cHRME MFE131 2.90 2N4121 1.50 7915UC 1.90
4068 1.00 74086 1.50 . 2.55 8641 5.95 CA3130E 2.90 BezeL 1.20 MFE3001 9.90 2N4123 1.50 7915KC 2.50 PEEC H CHI P
4069 1.00 74C89 9.90 a 3.95 8741 57.50 CA3130T 3.50 ? MFE3003 6.95 2N4236 1.90 7918UC 1.90
4070 90 74090 = 2.90 4 3.95 8748 = 65.00 CAS140E 2.20 SPECIAL MJ413-5.90 = -2N4237 «1.90 7924UC_— 1.90 Contains the code recognition
4071 40 74C93 «2.90 4 3.95 8749 58.50 CA3140T 2.95 MJ802 7.50 = 2N4248 = 4078105 :80
we 8 HSM, 38: | use ESS CAUCE NS RENEE, 82, 53 LEB eroultto enable the projecttoplug
‘| 740107 2. el 3.95 8820 6.95 CA3401 1.00 NES! . “ 4
4075 ‘90 746150 7:50 ; 3.95 9830 «6.95 GA3900 1.20 NESS34AN4.95 MJ11011 9.90 2N4258 80 78L18. ~— ‘80 directly on to ded Alas Port, or
4076 150 74C151 5.95 5 8832 6.95 CA3905 1.75 MC3340 2.90 MJ11015 14.50 2N4355 50 7824 80 into an
4077 80 74C154 7.95 j 74S SERIES 8833 6.95 CA3909 2.95 MC3341 2.90 MJ11016 14.50 2N4356 50 79L05 1.20 1-9 10+ 100+
se 8 Mei Se . ee ae a
‘ 74C160 2.95 ‘ 1.00 5.95 LM3914 590 71 95 5. ‘ f $ $ $
4082 80 740161 2.95 . 1.00 ane 2.95 LM3915 5.90 76489 9.95 MJ15024 10.00 2N4402 30 © 79L24 1.20 27.00 26.50 26.00
4085 220° 740162 2.75 60 1.00 gT14 2.95 LM3916 5.90 8038 6.50 MJ2501 8.90 2N4403 .30 LM309K
4086 2.30 740163 2.95 é 1.50 8T26 3.00 LM3999Z 2.60 OM335 22.50 MJ2955 2.50 2N4416 1.90 (7805KC) 1.90
4093 75 740164 = 3.50 1.00 gT28 3.00 RL4136 1.95 OM350 12.50 MJ3001 8.00 2N4427 3.90 LM317T 2.50
4094 3.35 74C165 3.50 i 1.50 8T30 3.00 C4145 20.90 XR2206 8.95 MJ4032 1250 2N4919 2.90 LM317K 4.50 4i 25 6- 1 5
4095 2.40 74C173 2.50 00 1.00 gT96 1.80 C4194 3.90 XR2207 7.95 MJ4502 6.90 2N5088 1.00 LM317HV 9.50
4096 2.40 740174 = 2.50 Q 1.00 8T97 1.80 XR2208 6.90 MJE340 1.50 2N5089 1.00 LM323K 7.50 1-9 10+ 100+
4097 6.50 74C175 2.50 ; 1.60 cop XR2209 6.90 MJE3SO 1.90 2N5139 1.20 LM337T 2.90
4098 290 74C192 2.00 ; 1.20 CDP1802 16.50 XR2211 7.95 MJE371 2.90 2N5179 1.20 LM338K 10.50 $5. 95 $5. 50 $4. 95
4099 3.90 74C192 2.00 z 1.50 LHOOO2 9.50 CDP1864 17.50 XR2216 5.90 MJE521 2.50 2N5190 2.50 LM350T 6.50
4194 1.95 74C193 2.00 K 1.00 LHO042CH 9.50 XR2240 6.95 MJE700 3.50 2N5191 3.30 LM350K _ 8.50
4510 1.50 740195 2.00 ‘ 1.00 LH0070. 9.50 cpu XR2243 7.95 MJE800 290 2N5192 3.10 LM395K 22.50
4511 1.20 740200 14.00 dj 1.70 LHOO71 = 9.50 6502 15.00 XR8038 7.50 MJE2801 3.95 2N5193 2.50 LM396K 19.50
4512 1,10 740221 2.75 “ 1.70 TLOG1 1.50 6502A 15.00 95H90 8.50 MJE2955 4.90 2N5194 2.95 78POSKC 16.50 4 1 64
4513 265 74C240 3.75 : 1.20 TLO62 2.90 6522 15,00 11C90 16.50 MJE3055 3.90 2NS5195 3.30 79HGKC 16.50
4514 2.90 740244 3.95 . 0.80 TLOG4 4.90 6522A 15.00 LM7555 2.90 MJE13005 5.90 2N5210 1.50 78S40 3.50 1-9 10+ 100+
4515 2.90 74C373 4.75 ‘ 1.20 TLO71 1.20 6532 14.00 LM7556 3.50 MJE13007 7.90 2N5245 1.50 MC1496L 14.50
4516 1.45 740374 4.45, ‘ 1.20 TLo72 290 6551 12.90 MC10116L 1.50 MJE1300912.50 2N5303 8.50 $2 25 $1 95 $1 75
4517 8.75 74C901 3.00 ; 1.30 TLO73 «=—-3.20 6800 6.00 LM13600 3.95 MPF121 2.50 2N5401 150 scree . . .
4518 2.50 74C902 2.50 ‘ 160° TLO74 = 4.90 6802 7.00 LF13741 80 =MPF131 2.50 2N5S457 1.00 ‘razacs
4519 1.90 740903 2.50 80 2.50 TLOB1 1.90 6808 1250 LF13741H 1.50 MPSA0S 1.00 2N5458 90 sci4iD 1.90
4520 1.20 740904 2.50 : 1.30 TLOB2 2.50 6809 10.00 DM2502 22.50 MPSA06 1.00 2N5459 90 ScCi4iE 1:95
4521 3.90 74C905 15.00 : 130 TLOB3 = 2.90 «6810 3.50. SAK140 9.50 MPSA10 1.00 2N5461 90 ScCi42E 2.95 27 1 2 8
4522 1.90, 74C906 2.90 i 1.20 TLog4 = 3.45 6821 5.50 ZN414 1.95 MPSA12 1.00 2N5462 90 Sc146D 2.85
4526 1.85 74C907 2.90 i 1.40 TL494 = 4.90 «6840 6.50 ICL7106 19.50 MPSA13 1.00 2N5485 90 Scis0D 4.95 1-9 10+ 100+
4527 2.65 740908 2.75 ‘ 1.30 TCA220 9.50 6845 12.50 ICL7116 19.50 MPSA14 1.00 2N5486 90 §C151D 2.95
4528 1.15 74C910 14.00 i 3.30 TCA280 4.50 6847 3.50 ICL7117 21.50 MPSA20 1.00 2N5489 1450 Sc152D 6.90 7.50 7 00 6 50
4558 2.25 74C911 12.50 4 3.30 TDA1024 2.80 6850 7.90 ICL7611 6.95 MPSA42 1.00 2N5590 2650 G1o3vY 90 . . .
4584 85 74C912 12.50 i 190 TA7205P 3.90 6875 15.00 —‘ICL7660 5.90 MPSA43 1.20 2N5591 29.50 Cio3B ‘90
4585 210 "74C914 4.50 74LS139 80745151 3.10 TEA1002 17.50 ZB80CPU 5.00 ICM7211 1250 MPSA55 1.00 2N5641 19.50 Ci06B ‘90
7AC915 4.00 74LS145 2.10 748153 2.00 UAAI70 5.95 ZBOACPU 5.00 ICM7216A69.50 MPSAS6 1.00 2N5656 250 C1220 2:50
74 SERIES 74C917 15.50 74LS147 2.50 748157 3.10 UAA180 3.75 ZBOBCPU 12.00 ICM7216B69.50 MPSA63 1.00 2N5770 30 C122E 2.95
7 80 74C918 2.90 741S148 1.90 745158 3.10 LM10CH 7.50 Z80P10 4.50 ICM7226A 48.50 MPSA65 1.00 2N5777——s:*11.50 C260D 8.50 7 BS
7401 80 74C920 12.50 74LS151_ 1.20 748160 5.90 LM301 1.00 Z80AP10 4.50 \CM7227A 19.95 MPSA92_ 1.00 2N5830 30 C260E 9.90 1-9 10+ 4100+
7402 80 740921 12.50 74LS152 1.95 745161 5.90 LM301H 1.50 ZB0CTC 5.50 MPSA93 1.20 2N5831 += .30. 2N2646 «1.95
7403 80 740922 7.50 74LS153 1.00 748162 7.90 LM302H 6.50 Z80ACTC 550 ANALOGS MPFi02 (90 2N5873. «1.40 ««-2N2647 2.50 19 50 18 50 17 50
7404 ‘80 74C923° 7.90 74LS154 2.95 748163 7.90 LM305H 1.50 Z80DMA 16.00 DIGITAL MPF103 90 2N5874. «1.70 © 2N6027. «90 5 7 i
7405 ‘80 74C925 14.95 74LS155 1.00 74S168 11.50 LM307CN 1.00 Z80ADMA 16.00 ADCO800LCN MPF105 90 =. 2N5944 (29.95
7406 80 740926 14.95 74/5156 1.50 745169 11.50 M308. 1.00 ZB0AS10 13.00 22.50 MPFI06 90 2N5945 39.95 crysrars
7407 80 740927 9.90 74LS157 1.10 745174 4.50 LM308H 1.80 280S10 13.00 ADCOBOILCN MPFi09 (90 2N5946 44.95 {mHz 9.50
7408 60 74C928 9.00 74LS158 1.00 74S175 4.50 LM309K 2:90 AD570 69.50 23.95 MPSLO1 1.50 2N5961 1.90 14.932MHz 6.50
7409 60 74C929 9.50 74LS160 1.00 748181 8.50 LM310N 3.20 ADS90 9:50 ADCOSOSLCN” = MPSLS1 1:50 2N6O27 1.00 MHz 5.90 CA3130E
7410 60 74C930 2.75 74LS161 80745182 3.40 = LM310H 3.20 AD7524_17.50 MPSU02 1.75 2N6049 1.90 2.3040MHz 6.50 1 100
741 70 740932 2.50 74LS162 1.50 74S199AN 4.10 9 LM3it 1.00 AY-3-8910 14.50 AapcosoaLcn MPSU52 1.90 2N6080 21.50 2.4576MHz 5.50 1-9 0+ +
7412 70 740941 2.50 74LS163 1.10 745189 8.50 LM311H 1.80 AY-3-2513 14.50 6.50 MPSU56 1.75 2N6083 26.90 2'7648MHz 4.90 1
7413 70 74C989 8.90 74LS164 1.40 745194 3.30 = LM317T 2:50 MSM583216.50 ADCOB08LCN MP131 2.75 =. 2N6084. 37.90 3MHz 4.90 $1 .95 $1 75 -50
7414 80 74LS165 1.50 748195 2.90 LM317K 4.50 MM58174 19.50 14.95 MRF221 19.50 2N6122) 1.90 3.5795MHz 2.50
7416 80 74F SERIES 74LS166 2.55 74S196/82590 LM318 = 4.90 MM5309 14.50 ADCO820LCN MRF237 5.90 2N6125 1.90 3.93216MHz 4.90
7417 80 74F00 79 74LS169 2.45 4.90 LM324 1.00 MM5369 4.95 24.95 MRF238 29.50 2N6130 1.90 4MHz 2.90
7420 60 74F02 79 74LS173 1.20 74S197/82591 M325 4.50 FDI771 19.00 DACO800 4.95 MRF245 53.50 2N6133 1.90 4.194304MHz
7425 90 74F04 92 74LS174 1.20 4.90 [M326 4.50 FD1791 (0876), DACO808 4.95 MRF455 37.00 2N6256 14.50 2.90 61 16 LP- 3
7427 80 74F08 79 74LS175 1.20 748201 9.90 LM329DZ .90 DACHESAECN MRF475 12.50 2N6259 = 13.50 4.433618MHz
7430 70 74F10 79 74LS181 4.00 TAS2IAAN LM344Z 1.90 FO1793 (0877) MRF603 19.50 2N6274 29.50 2.90 (150ns)
7432 1.00 74F11 79 74LS190 1.50 P.O.A. LM335Z 2.20 DACIO20LGN MRF641 49.00 2N6378 = 4.90 4.44MHz 2.90 10+ 100+
7437 1.00 74F20 79 74L$191 1:20 748225 10.90 295 FD1795 39.00 19.95 MRF646 53.00 2N6425 4.50 4.75MHz 2.90
7438 1.00 74F32 79 74LS192 1.20 748226 7.90 LM338K 12.50 FD1797 39.00 DAC1220LCN MRF901 2.90 2N6578 4.90 4.915200MHz $3. 95 $3. 75 $3. 50
7440 1.00 . 74F64 ‘79 -74LS193 1.20 748240 6.90 LM339 1.20 WD1691 29.50 19.95 MPF131 1.90 6.90
7442 1.50 74F74 89 74LS194 1.20 745241 6.90 M348 1.80 WD2143 24.50 TIP31A = 1.00 2SA683_ «1.50 4.9°.62MHz 2.90
7445 1.95 74F86 119 74LS195 90 74S244 9.90 LM349 «2.95 WD1931 2250 TRANSISTORS TIP31B 1.00 2SC2028 3.95 500MHz 2.90
7446 120° 74F109 99 74LS196 90 748251 3.90 LM350K 10.50 WD1933 34.00 ACI25 1.20 TIP31C 1.00 —-2SC2029 3.95 Ss 0688MHz 2.90
7447 150 74F138 1.79 74LS197 1.75 748253 4.90 LM351N 1.00 WD1983 14.75 ACI26 1.20 TIP32A 1,00 2SC2166 4.95 é6MHz 2:90 NESS 3 4 AN
7449 1.20 74F139 1.79 74L $221 2.00 748257 3.30 (M353. 2:50 WD1993 59.00 ACI27 1.20 TIP32B «1.00 ««-2SC1730 1.95 6414MHz 290
7450 1.00 74F151 1.79 74LS240 1.90 748258 3.30 LM356N 2.40 WD2123 2650 ACI28 1.20 TIP32C 1100 2SC1969 6.30 6.6670MHz 2.90 1-9 10+ 100+
7451 1.00 74F153° «1.79 74LS241 1:90 748260 290 Lmas7 2.40 50 29.50 ACI87 1.50 TIP4iC 1.90 2SC1973 3.95 MHz 2.90
7473 1.00 74F157 ='1.79 -74LS242 1.90 748274 P.O.A. LM358 1.40 Ter1602 (81883) AC188 1.50 TIP42A 1.90 VNS8AF 3.95 8.867238MHz $1 95 $1 85 $1 75
7474 100° 74F158 «1.79 74LS243 1.90 748275 P.O.A. LM361 3.50 8: ACI49° 3.40 «= TIP42C.-=— 1:90 ©. 2SC372_—1.95 4.90 . . .
7475 1.20 74F175 2.78 74LS244 1.50 74S280 5.90 M377 4.90 TR1853 8.90 AD161 2.90 TIP49 1.90 2SC495 2.95 10MHz 4.90
7476 150 74F181 5.98 74LS245 2.60 745281 P.O.A. M378 6.95 COM811624.00 ADI62 290 TIP5O 2.20 2SC710D 1.95 10.6445MHz
7485 180 74F182 2.73 74L S247 1.30 748283 7:90 LM3808 pin BR1941 23.00 AFI18 2.90 TIP53 250 2S8C73_ 1.95 4.90
7486 1.80 74F189 = 7.44 74LS248 «61.50 74S287 4.90 1.80 CRT8002A BC107 50 TIPT11 1.50 2SC9O0F 1.95 11MHz 2.90 | N s 8 2 S 0
7489 3.90 74F190 4.86 74LS249 1.60 745288 4.90 LM380 14 pin 59.90 BC108 50 = TIP112 1.50 2SC945A 1.95 12MHz 2.90 m
7490 1.20 74F191 4.86 = 74LS251 1.50 745299 13.90 1.90 Bcie2t 40) TIP116— 1.50 2SC1014 2.50 = 14.31818MHz 10+ 100+ 3
7493 1.20 74F194 2.41 74LS253 1.20 748301 13.90 LM381 3.50 MEMORY BC212 30 TIP117 1.50 2SC1017 4.95 4.90 g
7495 1.20 74F241 3.72 74LS257 70 «= 74S314 ~P.O.A. LM382 3.50 2102 2.50 BC318 30° -TIP120.- 1.50 = 2SC 1018 4.95 15MHz 4.90 $24, 50 $22. 50 $20. 50 a
7497 2.75 74F243 4.34 7418258 1.20 748330 P.O.A. LM383 5.95 2114 4.95 BC320 40 = TIP122 1.50 2SC1061 2.95 16MHz 4.90 ge
74100 1.65 74F244 «3.72, 74LS259 1.50 745331 P.O.A. LM384 3.50 2708 12.50 BC327 30 0 -TIP125 1.50 2SC1096 2.95 18MHz 4.90 °
74107 1.20 74F251 1.93 74LS261 250 748373 9.90 M386 1.95 2716 9.90 8C328 3000 TIPI27)»—-1.50 = 2SC1173 2.95 — 18.432MHz 4.90 3
74109 90 74F253° 1.93 74LS$266 1.20 748374 9.90 LM387A 3.95 2732 8.95 BC337 40 TIP145 «3.40 «=. 2SC 1226 2.95 20MHz 4.90 3
74110 1.50 74F257 1.93 74LS273 1.95 745381 9.90 M387 2.00 2764 7.95 BC338 40 TIP2955 3.50 2SC1306 6.30 24MHz 4.90 AM 791 1) 7
74121 ‘90 74F258 1.93 74LS275 6.80 748387 3.30 LM390 2.95 27128 8.00 BC546 40 TIP3055 3.50 2SC1419 2.95 27MHz 4.90 fe}
74122 90 74F350 «4.34 = 741S279 60 = 74S412/8212 LM391 2.90 4116 3.95 BCS547 20 28C1449 1.95 32MHz 4.90 (WORLD MODEM CHIP) 2
1.50 74F352 1.93 74LS$280 2.60 5.90 LM393_ 1.00 4164 3.95 BC548 20 aN 2SC1674 1.95 36MHz 4.90 a
1.00 74F353° «1.93 74LS283 1:50 748428/8212 LM394CH 6.95 6116 5.00 BCS549 20. 2N301 «= 4.00. 2SC1307 6.90 —32.768MHz 4.90 24.95 x
1.80 74F373° 4.84 = 74LS290 1.50 7.90 LM395T 9.95 6264 8.00 BCS550 40 2N697 1.00 28D: 3.95 Py @
1.00 74F374 = 4.84 74LS293. 1.30 748470 = 9.90 LM396K 22.50 58725 (6116) BC556 40 2N918 1.00 280325 2.95 not
150 74F399 2.78 = 74LS295 1.75 748471 9.90 F398 5.90 4.00 BC557 :20 2N1304 «1.00 ©. 2SD350A ‘5. g
1.45 74F521 4.22 74LS297 6.50 748472 9.90 NE544 6.50 BCS58 .20 280525 3.95

2

MINIATURE HEATSINK!
A great little fellow if you are short of
space. Great price too, because we

import direct so you save!
Cat. 10606 1-9 10+
$0.40 $0.35

=
COMPUTER CABLE
CIC6 6 conductor computer
interface cable. Colour coded with
braided shield.

(to 1E422 specifications).

Copper conductor 6 x 7/0.16mm.
1-9 metres 10+ metres

$1.90/m $1.70/m

CIC9.100 9 conductor computer
interface cable. Colour coded with
mylar shielding. 9 x 7/0.16mm.

1-9 metres 10+ metres

$2.50/m $1.95/m

CIC12 12 conductor computer
interface cable. Colour coded with
mylar shielding. 12 x 7/0.16mm.
1-9 metres 10+ metres

$2.70/m $2.50/m

CIC16 16 conductor computer
interface cable. Colour coded with
mylar shielding. 16 x 7/0.16mm.

1-9 metres 10+ metres

$3.90/m $3.40/m

CIC25 25 conductor computer
interface cable. Colour coded with
mylar shielding. 25 x 7/0.16mm.
1-9 metres

$4.90/m

10+ metres

$4.40/m

RAINBOW CABLE

Suitable for IDC connectors.
Cat.No. Description $/metre
W12714 28AWG14W $1.80
w12716 28AWG16ew $1.80
W12720 28AWG20W $2.20
W12726 28AWG26W $2.90
W12734 28AWG34W $3.60
w12740 28AwG4ow $4.40
999803

e
COUNTER
Cat. $12.95

MAINS MUFFLER
Sudden mains disturbances can
seriously affect your computer
equipment, and stored data. So why
risk It when you can have a Mains
Muftler, particularly when the cost of
one failure is likely to be greater than
the purchase price! So vanish those
dangerous clicks and voltage
spikes forever with the Mains
Muffler!
SPECIFICATIONS:
Maximum total load

1000W 4 AMP 250V 50Hz
Outlet Sockets

Attenuation: 1SOKHz - 47dB

500KHz - 68dB
10MHz - 66dB

Dual T Section:

VOR Transient suppression

Surge capacity 200 Amp 8 x 20uS

2 WAY Cat. X10089 .... $199
4 WAY Cat. X10090 ... $299

HIGH EFFICIENCY

RADIAL FIN HEATSINK
Black anodised with a thick base
plate, this radial fin heatsink can
dissipate large amounts of heat for
maximum efficiency. Designed by
Rod Irving.

105x30mm Cat.H10520 $ 3.50
105x75mmCat.H10525 $3.50
105x100mm Cat. H10529 $ 4.90
105x140mm Cat. H10534 $ 6.50
105x150mm Cat. H10535 $ 6.75
105x170mm Cat. H10538 $ 7.95
105x195mm Cat. H10542 $ 9.90
105x200mm Cat. H10543 $ 9.90
105x225mm Cat. H10546 $10.50
105x300mm Cat. H10549 $12.00
105x600mm Cat. H10560 $24.95

RS232 GENDER

CHANGERS _
@ Saves modifying or replacing
non-mating PS232 cables.
@ All 25 pins wired straight through

Cat. X15650 Male to Male
Cat. X15651 Male to Female
Cat. X15652 Female to Female
Normally $19.95 each
Only $14.95

RS232C NULL MODEM
ADAPTOR

@ Male to female connections
@ Pins 2 and 3 reversed
@ All 25 pins connected

Cat. X15657 Male to Male

Cat. X15658 Male to Female

Cat. X15659 Female to Female
Normally $22.95
Only $14.95

RS232 WIRING
ADAPTOR BOX

@ Male to female

@ 25 Detachable plug on leads

@ 2 mini jumpers

@ Ideal for experimenting or

temporary connections
Cat. X15665 ...... Normally $39.95

Only $29.95

RS232 MINI JUMPER

PATCH BOXES
@ Interface RS232 devices
@25 pe inputs

@ 25 leads with tinned end supplied

© Complete with instructions

Cat. X15653 Male to Male

Cat. X15654 Female to Male

Cat. X15655 Female to Female
Normally $25.95
Only $19.95

NG
RS232 MINI TESTER

‘@ Male to female connections

@ All pin wired straight through

© Dual colour LED indicates activity
and direction on 7 lines

®@ No batteries or power required

T.D. Transmit Data

D.S.R. Data Set Ready

R.D. Receive Data

C.D. Carrier Detect

R.T.S. Request to Send

D.T.R. Data Terminal Ready

C.T.S. Clear to Send

Ci

at. X15656 ...... Normally $39.95
Only $29.95

ee ae

ANTISTATIC
SOLDER SUCKER
@ Light weight
© Sturdy construction
@ Easy to remove tip
@ Excellent value for money!

Cat. T11281 eecceeeeeeee: $13.95

ELECTRONIC DOOR
ALARM AND CHIME

Electronic control system with
powerful in-built 100dB alarm.
Changeable 3 digit, push button,
secret code controller that is tamper
proof. 3 function switch provides off
position, chime and 7 seconds delay
entry. Emergency panic button.
Suitable for left or right hand door
opening. Simple installation, no
wiring required. Low current 15mA
at 9V. Operates on 9V battery.

Cat, $2722? aecceesseeeer $44.95

EK

CORDLESS

RECHARGEABLE

SOLDERING IRON

© Built in solder point illumination

@ Easy replacement of solder tip

© Protective stand which also
functions as charging unit

© Sponge pad attach to stand

@ Plug pack power adaptor

@ Includes Nicad battery

@ Instructtion manual

@ 12 months warranty

Cat. T12480 ...... Normally $79.95

SPECIAL, $69.95

—————

eo

FLUORESCENT WORK &
EMERGENCY LIGHT

@ Suits cars, boating, caravan,
camping etc.

@ Shatterproof, glare free

© Cigarette lighter plug and alligator
clips

@ 12V DC, 8 watt, transistorised

Cat. A15052 $25.95

ELECTRONIC CASSETT
DEMAGNETISER
Cat. A10006 oo... $22.95

FREE STANDING, FOLD
UP MAGNIFIER

An ecconomically priced “hands free”
magnifier, lets you take care of all
those tricky fine detailed jobs so
often encountered in electronics, or
any of many other practical uses
such as home, work, hobbies etc.
Cat. T12083 Normally $14.95

SPECIAL, ONLY $12.95

SEMICONDUCTORS!
Always check with us
before you buy!

1-9 O+ 100+
$9.95 $8.95
$8.95 $7.95
$7.95 $6.95

x $6.25

$10.00
$2.95

2716
2732
2764
27128
27256
4116

MEL9501
Have you blown up your Apple drive
by plugging it in backwards or not
turning off the power while changing
boards? We have the MEL9501 chip!

SPECIAL, ONLY $29.95
8087

Genuine Intel chips with manual
and data sheets packed in boxes!
8087-3 (4.77MHz) .
8087-2 (8MHz)
8087-1 (10MHz) .
80287-3 (6MHz) .
80287-7 (8MHz) .
8087-3 (4.77MHz) .

NES534A
SCOOP PURCHASE!!!
1-9 10+

$1.95

WORLD MODEM CHIP
Cat. U21614 ........ Normally $49.50

Save $25, SPECIAL $24.95

PROGRAMMABLE

24 HOUR TIME SWITCH
® 48 switching possibilities per day
@ 240V AC, 2400 watt, 10 amp
© Suitable for turning on.
Heaters/Coolers
pool filter
electric blankets
cooking appliances
waking you, even making the coffee!
lights etc for security while you're
away from home!
@ Bargain Price!

Cat. M22002 only $19.95

TV INTERFERENCE
FILTER

Cuts CB/Ham signals interference

Cat. L11048 $5.95

—s

10dB IN-LINE COAXIAL
AMPLIFIER

Reduces loss from splitters and long
cable runs. Suitable for use with
antennas, coaxial feed lines and
VCR's. A/C adaptor included.
SPECIFICATIONS:
Frequency: Range: 5-900MHz
Gain: 10d
Power Requirements: 12V A/C
Adaptor (included)
Input Impedance: 75 ohm
Output Impedance: 75 ohm

Cat. L15043 $44.95

UHF/VHF/FM ANTENNA
AMPLIFIER AND 2 WAY
SPLITTER.

Covers all Australian frequencies.
Suitable for use in houses,
caravans, boats etc

@ 1x 75 ohm input

@ 2x 75 ohm output.

© Gain 2 x 6dB.

@ Maximum output 2 x 96dBuV.

Cat. L15041 $39.95

UV EPROM ERASER

Erase your EPROMs quickly and

safely. This unit is the cost effective

solution to your problems. It will

erase up to 9 x 24 pin devices in

complete safety, in about 40 minutes

(less for less chips).

Features include:

© Chip drawer has conductive foam
pad

@ Mains powered

@ High UV intensity at chip surface
ensures EPROMs are thoroughly
erased

@ Engineered to prevent UV
exposure

@ Dimensions 217 x 80 x 68mm

WITHOUT TIMER
Cat. X14950 ......... Normally $119
Special, $89

WITH BUILT-IN TIMER
Cat. X14955 $139

Special, $119

—$ ae
cy~

CAR ANTENNA BOOSTER

@ In-line instalation

@ 12V boosts 100%

Cat. A12073

.. $7.95

NICADS!
Size Desc. 1-9 10+
AA 0.5 A.H. $2.95 $2.75 $2.25
C 1.2 AH. $7.95 $6.50 $6.25
D 1.2 AH. $7.95 $6.50 $6.25

100+

UNIVERSAL BATTERY
CHARGER AND TESTER

Save money on expensive batteries
with this universal battery charger.
Features include meter tester, and
provisions for D, C, AA, AAA, N,
button and cell batteries, 9V and 6V
(square types). Comes complete
with detailed instructions.

Cat. M23533 oo. $29.95

PCB Coating ‘201'
Cat. N11040
Freezing Spray ‘202’
Cat. N11042 .... a
Insulating Varnish ‘203’
Cat. N11043 .... $7.95
Electric Motor Cleaner ‘204’

Cat. N11044 oes $6.95
Electronic Super Clean (Freon) ‘205'
Cat. N11047 ....
Flux Remover ‘206’

Cat. N11049 ... $6.95
Elec Contact Cleaner & Lube ‘207’
CatcNI1054 assesses $5.95
Silver Cote ‘208°

Cat. N11054

Formula “66” ‘535'

Cat. N11057 ... $5.95
Clear Coat Plastic Spray ‘540°
Cat. N11059 oe $6.95

SENNHEISER
HEADPHONES!!

The worlds best headphones are
Now available from Rod Irving
Electronics!! 3 models to choose
from, other models are available
on request! (Phone Tony DiPaolo
on (03) 543 2166)

SENNHEISER HD 40
The HD40 is feather light, at just 609!
This HiFi stereo headphone is
uncommonly convenient to use. Its
systems can be rotated so it can fit
into any drawer. It is also available
as a TV headphone.
SPECIFICATIONS:

Frequency Range: 22 - 18,000Hz

Impedance: 6000hm

Distortion Factor: Approx. 1.5%;
pressure on ear; approx, 1.3 N

Weight: Approx. 60g

Length of lead: 3 metres

Cat. A10815 vases $49.95

White durable plastic, 8 ohms
Cat. C12010 Normally $11.95
SPECIAL, ONLY $9.95

ri

Rod Irving Electronics

48 A'Beckett St, MELBOURNE
Phone (03) 663 6151

425 High St, NORTHCOTE
Phone (03) 489 8866

Mall Order and Correspondence:
P.O. Box 620, CLAYTON 3168

Telex: AA 151938

MAIL ORDER HOTLINE
008 335757
(TOLL FREE)

(STRICTLY ORDERS ONLY}

LOCAL ORDERS
& INQUIRIES
(03) 543 7877

POSTAGE RATES:

$1 - $9.99 $2.00
$10 - $24.99 $3.00
$25 $49.99 $4.00
$50 $99.99 $5.00
$100 $199 $7.50
$200 $499 $10.00
$500 plus $12.50

The above postage rates are for
basic postage only. Road Freight.
bulky and fragile items will be
charged at different rates

All sales tax exempt orders and
wholesale inquiries to
RITRONICS WHOLESALE.

56 Renver Rd, Clayton

Ph. (03) 543 2166 (3 lines)
Errors and omissions excepted

Apple and IBM are registered trade names

[Se cm

008 335757 TOLL FREE MA

IBM* XT COMPATIBLE
COMPUTERS *°™ $795*

Check these features and our prices. We're sure you'll agree
they're exceptional value for money!

@ Assembled in Australia! @ AT style keyboard

@Testedbyusfor24hours © Operating manual
prior to delivery! © 8 Slot motherboard

@ 150W power supply © 6 Months warranty!

(Japanese drives available for an extra $50 each)

*$795 COMPATIBLE COMPUTER

256K RAM Single Drive, Graphics and Disk Controller Card. $795

256K RAM COMPATIBLE COMPUTER
2 x 360K Disk Drives, Multifunction Card, Colour Graphics, Disk
Controller, 1 Parallel Port. (Includes Timer Disk) ........... $1,095

640K RAM COMPATIBLE COMPUTER
2 X 360K Disk Drives, Multifunction Card, Colour Graphics, Disk
Controller, 2 Serial, 1 Parallel Port. (Includes Timer Disk). $1,195

20 M/BYTE HARD DISK COMPATIBLE
COMPUTER

20 M/Byte Hard Disk, 360K Disk Drive(s), 640K RAM, Multifunction
Card, Colour Graphics, Disk Controller, 2 Serial, 1 Parallel Port.
Includes Timer Disk)

ingle 360K Floppy Disk Drive .

.. only $1,995
Dual 360K Floppy Disk Drives.

on only $2,150

IBM* AT COMPATIBLE

Assembled & Tested in Australia!

@ 1 M/Byte Main Board @6 MHz
@ 1.2M/Byte Floppy Disk Drive @ 80286 CPU
© Colour Graphics Display Card @ 8 Slots
@ Floppy & Hard Disk Controller @ 20 M/Byte Hard Disk
@ Printer Card and RS232 @ Keyboard
@ 200W Power Supply @ Manual
@ 6 Months Warranty

waa ni Ss sus omaha SOs swaps ag asaabansmaannapabs adipanesdiaapasans only $3,395

Now you can buy top quality 51/4” disks that are also
the cheapest in Australia! They even come with a 5
year guarantee, which indicates the quality of these
disks. So why pay 2-3 times the price for the same
quality?

MICRODOT 51/4” DISKS!

DESCRIPTION 1-9 BOXES 10+ BOXES

5%” S/S D/D $14.95 $13.95
51%” D/S D/D_ $18.95 $17.95

(SEND $2 FOR SAMPLE DISK!

MICRODOT 51/4” HIGH DENSITY

1-9 BOXES 10+BOXES 100+BOXES
49.95 $44.95 $39.95
(PER 10 DISKS) (PER 10 DISKS) (PER 10 DISKS)

51/4” D/S “NO FRILLS” DISKS
FROM 90¢ EACH!!

Bulked packed, Microdot D/S D/D without boxes, or brand name,
just their white card jacket!

10-99 DISKS 100+DISKS

1,000+DISKS
$1.20°° $1.10°°

$0.90°*
(SEND $2 FOR SAMPLE DISK!)
(TAX EXEMPT PRICES LESS 20¢ PER DISK)

31/2" “NO FRILLS” DISKS!
D/S D/D disks with white boxes but no brand name.
(These are a top name brand, but we can't tell you which.)

10-99 DISKS 100+DISKS 1,000+ DISKS

$42.50 $39.95 $35.00

(PER 10 DISKS) (PER 10 DISKS) (PER 10 DISKS)
(SEND $5 FOR SAMPLE DISK!)

(TAX EXEMPT PRICES LESS 40¢ PER DISK)

So

~

SEMICONDUCTORS!

Always check our prices

before you buy!

1-9 10+ 100+
2716...... $9.95 $9.50 $8.95
$8.95 $8.50 $7.95

$7.95 $7.50 $6.95
. $6.95 $6.50 $6.25
«$11.50 $10.50 $10.00
«+ $19.50 $18.50 $17.50
. $3.95 $3.50 $2.95

$2.25 $1.95 $1.75
41256 .... $4.95 $4.50 $3.95
5558pin $0.50 $0.40 $0.35

$3.50
$5.75
$3.75
$1.70
$3.75
$0.25

7406 ...... $0.40 $0.30
INS8250 $29.95 $27.95

MEL9501
Have you blown up your Apple drive
by plugging it in backwards or not
turning off the power while changing
boards? We have the MEL9501 chip!

SPECIAL, ONLY $29.95
8087

Genuine Intel chips with manual
and data sheets packed in boxes!

8087-3 (4.77MHz) .. $279
8087-2 (8MHz) .. $399
8087-1 (10MHz) $649
80287-3 (6MHz) $499
80287-7 (8MHz) .. $699

TELECOMMUNICATIONS
AUSTRALIAN STYLE
ADAPTOR CABLE

@ Australian socket to plug/socket
@ Length 10 metres
Cat. ¥16015 $14.95

TELEPHONE CURL CORD
@ U.S. plug to U.S. plug
© Replacement hand set cord

@ Length 4.5 metres

Cat. ¥16023 $6.95

TELEPHONE ADAPTOR
© Australian plug to U.S. socket
®@ Length 10cm

Cat. ¥16026 $5.95

TELEPHONE
EXTENSION CABLE UNIT

Allows 15 metres of telephone
extension cable to be neatly wound
into a protable storage container
The reel sits on a flat base and has a
handle to wind cable back on to it
after use. No tangles - no mess!
Ideal for the workshop, around.the
house, office, pool etc.

Cat. Y16013 $22.95

JUMBO 51/4” DISK
STORAGE

If you've got lots disks, you'll
appreciate the extra capacity of this
disk storage unit when it comes to
locating “that” disk!

Features...

@ 100 disk capacity

@ Smoked plastic cover

@ Lockable (2 keys supplied)

@ 9 Dividers/spacers

C16020 . only $24.95
16027 (Hinged Lid) $26.95

5a" DISK STORAGE
Efficient and practical. Protect your
disks from being damaged or lost!
Features...

® 70 disk capacity

@ Smoked plastic cover

@ Lockable (2 keys supplied)

@ Dividers/spacers
Cat, C16025 only $19.95

5 V4" DISK STORAGE
Efficient and practical. Protect your
disks from being damaged or lost!
Features...

@ 50 disk capacity

@ Smoked plastic cover

@ Lockable (2 keys supplied)

@ Dividers/spacers
Cat. C 16030 only $19.95

32" DISK STORAGE UNIT

@ Holds up to 40 x 312" diskettes

@ | ockable (2 keys supplied)
@ High impact plastic lid and base
@ Anu static

16040 only $19.95

2

31%” DISK STORAGE UNIT
@ Holds up to 40 x 31/2" diskettes
@ Lockable (2 keys supplied)

@ High impact plastic lid and base

Cat. C16035 ........ only $19.95

NE FOR CREDIT CARD ORDERS! LOCAL ORDERS & INQUIRIES CALL (03) 543 7877

RS232 GENDER
CHANGERS

® Saves modifying or replacing
non-mating RS232 cables.
© All 25 pins wired straight through

Cat. X15650 Male to Male
Cat. X15651 Male to Female
Cat. X15652 Female to Female
Normally $19.95 each
Only $14.95

RS232C NULL MODEM
ADAPTOR

@ Male to female connections
@ Pins 2 and 3 reversed
@ All 25 pins connected

Cat. X15657 Male to Male

Cat. X15658 Male to Female

Cat. X15659 Female to Female
Normally $22.95
Only $14.95

RS232 WIRING
ADAPTOR BOX

@ Male to temale

®@ 25 Detachable plug on leads

@ 2 mini jumpers

@ Ideal for experimenting or
temporary connections

Cat. X15665 Normally $39.95

Only $29.95

RS232 MINI JUMPER

PATCH BOXES
@ Intertace RS232 devices
@ 25 pin inputs
@ 25 leads with tinned end,supplied
@ Complete with instructions

Cat. X15653 Male to Male

Cat. X15654 Female to Male

Cat. X15655 Female to Female
Normally $25.95
Only $19.95

RS232 MINI TESTER
@ Male to female connections
© All pin wired straight through
@ Dual colour LED indicates activity
and direction on 7 lines
@ No batteries or power required
D. Transmit Data

T
D.S.R, Data Set Ready

R.D. Receive Data

C.D. Carrier Detect

R.T.S. Request to Send
D.T.R. Data Terminal Ready
C.T.S. Clear to Send

Cat. X15656 Normally $39.95
Only $29.95

1B ai
q se
PRINTER LEAD FOR IBM*
@ Suits IBM* PC XT and compatibles

@ 25 pin “D" plug (computer end)
to Centronics 36 pin plug

Gari aeee” SSE

[
oi
["

UV EPROM ERASER

Erase your EPROMs quickly and

safely. This unit is the cost effective

solution to your problems. It will

erase up to 9 x 24 pin devices in

complete safety, in about 40 minutes

(less for less chips).

Features include:

@ Chip drawer has conductive foam
pad

@ Mains powered

@ High UV intenstly at chip surface
ensures EPROMs are thoroughly
erased

@ Engineered to prevent UV
exposure

@ Dimensions 217 x 80 x 68mm

WITHOUT TIMER
Cat. X14950 Normally $119
Special, $89

WITH BUILT-IN TIMER
Pats. XVG9ES ...scccersesrereees $139

Special, $119

“IBM* AT COMPATIBLE”
KEYBOARD

@100% IBM* PC, XT compatible
@ Low profile keyboard design
© Proper placement of shift keys
with large key tops to suit
professional typists.
@ 3 step height/angle adjustment
@ Cherry brand TS-M00001 19mm
low profile switches, meet 30mm.
ergonomic requirement and
provides high performance and
maximum reliability.
© Curl lead plugs siraight into PC: XT
@ 3 Status displays
Just like the ‘Real McCoy” only at
a fraction of the price!

Cat.X12020 only $129

IBM* XT & AT
COMPATIBLE
EXTENDED KEYBOARD
(105 KEYS)
These new keyboards are both XT
and AT compatible!
® 20 Dedicated function keys
@ Enlarged "Return" and "Shift" key
© Positive feel keys
@ Low Profile Design, DIN standard
@ Separate Numeric and Cursor
control keypads
@ Additional Functions
Key-in-lock, Audio Beep, Previous
Word, Next Work, Fast Repeat,
Line Feed, Pause, Clear Screen,

Reset.
CX RBE CIAL, ONLY 8198

APPLE* Il SERIES
COMPATIBLE JOYSTICK
These joysticks have adaptor
connectors to suit the Apple II, IIc, lle
and Il + computers. Features include
selectable “spring centring” or "free
floating”. Electrical trim adjustments
on both axis, 360° cursor control
and dual fire buttons

$49.95

Cat. C14201

JOYSTICK FOR IBM
Features Selectable “Sprin:
centering” or “free floating”. Electrical
trim adjustments on both axis.

360 degree cursor control

Cat. C14205 $49.95

008 335757 TOLL FREE MAILORDER HOTLINE FOR CREDIT CARD ORDERS! LOCAL ORDERS & INQUIRIES CALL (03) 543 7877

NEW! NEW! NEW! NEW!

20M/BYTE HARD DISK CARD

XT compatible, simply plugs straight

Ip to your computer!
OR ersineaeseoniaaniaay

sseseeeere $1,295
Colour Graphics Card
Cat. X18002 «0.0.0.0... $129
Graphics Card
(Hercules compatible)
Cat. X18003 0... $165

Floppy Disk Drive Controller Card
(2 Drives, 16 Bit)
Cat. X18005 oo. $59

Floppy Disk Drive Controller Card
(4 Drives, 16 Bit)

Cat. X18006 . sereerreanneres S65
High Resolution Mono Card
Cat. X18007 oo... cecseceees $199

Colour Graphics & Printer Card
Cat. X18010 oor $149

768kB RAM Card (without memory)
Cat. X18012 oe $89

Printer Card

Cat. X18017 $34.95
Game W/O Card
Cat. X18019 .. $37.95

XT Motherboard (without memory)
Cat. X18020 o.eecceceeree $225

Clock Card
Cat. X18024 00.0.0... $57.50

RS232 Card (without cable)
Cat. X18026 ....... woe $5!

RS232 & Clock Card

Cat. X18028 ....... $95
XT Turbo Motherboard

(without memory)

Cat. X18030 0... . $275

Multi /O & Disk Controller Card
Cat. X18040 svesee $179

VO Plus Card

Cat. X18045 . $129
768K Multifunction /O Card
(includes cable but not 41256 RAM)
Cat. X18050 ......... Fi $199
Hard Disk Controller Card

Cat. X18060 ........ $195

Enhanced Graphics Adaptor Card
256K RAM on board

Cat. X18070 .........0. see $375
64K Printer Buffer Card
Cat. X180?? $139

Enhanced Graphics Adaptor Card
(Award Bios)
Cat.X ..

$495,

PRINTER CARD
Cat. X17029 ...... $89
DRIVE CARD
Cat. X17019 .. $79
80 COLUMN CARD
Cat. X17025 . «. $85

SUPER SERIAL CARD
Cats XAZOSS: ssirtenrsprrasrsssveney SUT

RGB CARD
Cat. X17039 occ sreseeres S79
PAL COLOUR CARI
Cat. X17027 oo. $95
Z80 C/M CARD
Cat. X17041 neces $59
80 COLUMN/64K CARD
CBE icrarasasasaunrerinis $69
64K/128K CARD
COUR: izcvissssrasaensncare ve $69

Half the price of other brands!!
Relieve eye strain and headaches
and increase productivity with these
Anti Glare Screens. Suitable for 12"
monochrome and colour monitors.

Cat. X99995 oo... $24.95

@ 1 M/Byte unformatted,

(640K formatted),
© Double sided, double density,
© Access Time 3m/sec
ee $265

© Switchable 1.6 M/Byte to 1 M/Byte
unformatted
1.2 M/Byte to 720K _ formatted
© Double sided, double density,
@ AT compatible
Cat. C11906 siete, $295

© Double sided, double density,
@ 1.6 M/Byte unformatted.

Cat. C11908 sessssssseene $T95

Tired of paying out more for
Japanese Disk Drives? These
“direct import” Hong Kong disk drives
are the solution! They feature
Japanese mechanical components,
yet cost only a fraction of the price!

Cat.No. Description Price
C11801 500K ...... Normally $199

SPECIAL, ONLY $179
C11805 1.6 M/Byte

$259

——y

NEC drive with DTC controller card
Cat. X20010 w..csees WAS $995,
SPECIAL, ONLY $850

“IBM is a registered trade mark

Japanese Chinon mechanism,

compatible with Apple 2+
Cat. X19901 . Normally $225

SPECIAL $199

(‘Apple is a registered trade mark.)

We have just imported 50,000.
So you get to save a small fortune!

DB25 MALE (P10900)
1-9 10+ 100+

$1.50 $1.20 $1.00
DB25 FEMALE (P10901)

1-9 10+ 100+

$1.70 $1.40 $1.20

A quality 12” TTL monitor, with a
high contrast, non-glare screen at
a very reasonable price!
SPECIFICATIONS:
CRT: 12” diagonal 90° deflection,
non-glare screen.
Active Display Area:
216(H) x 160(V)mm
Display Characters: 2,000
(80 characters x 25 lines)
Scanning Frequency:
Horizontal: 18.432 + —0.1KHz
Vertical: 50 HZ + —0.5%
Description Cat.No. 1-9 10+
Green X14517 ....... $189 $179

Amber X14518 ...... $189 $179

@ Restores order to the top of your
desk or work area

@ Made of white plastic coated steel
@ Stores up to 900 continuous sheets
®@ Allows perfect paper feed

@ Allows easy examination of print out
21050 (10") ...... only $49.95
€21050 (15") ...... only $79.95

(Printer and paper not included)

CP80, BX80, DP80, BX100, MB100
ALL A CRAZY LOW $9.95

p——L

@ Suits IBM" PC XT and compatibles
@ 25 pin “D” plug (computer end)
to Centronics 36 pin plug
Cat.P19029 1.8metres $17.95
Cat.P19030 3 metres .... $22.95

sent.

Sao ome

-Mitchell Waite, David Fox

If you are learning programming or
have dabbled in the popular
language BASIC and wish to learn
the capabilities of Pascal, this book
is definitely written for you. Written
and illustrated with a touch of
humour, the informative text
describes Pascal program structure,
Pascal variables, Pascal procedures,
and many other features. There are
chapters on decision making
statements, numeric functions,
string functions, arrays and sets, and
much more. The eight appendices
present facts about the advantages
and disadvantages of Pascal,
components of a Pascal system,
interfacing assembly language
routines, and other useful
information

CAUB; spssissnoncssaoneane $24.95

High quality |BM* compatible
monitors, great with VCR's too!
SPECIFICATIONS:
CRT: 13", 90° deflection colour
Input Signal:
Video Signal: Separate video signal
Video: Positive
Sync.: Positive
Input Level: TTL Level
Scanning Frequency:
Horizontal: 15.7KHz
Vertical: 60Hz
Display Size: 245(H) x 182(V)mm
Resolution:
Horizontal: 640 dots
Vertical: 200 lines

Cat. X14530 secs $695

© Serial Impact Dot Matrix
© 140C.P.S

Near Letter Quality Mode
@ 1.4K Buffer

Cat. C20040 .....

con, $595

@ 120C.P.S.

@ Pica or Elite character set

© Print Modes: NLQ, Dot Graphics,
Proportional Font, Draft

@ Proportional Printing

@ Reliable and Compact

® Proportional Printing

@ Logic Seeking

@ 1K Printer Buffer

Cat. C20035 only $595

Quality paper at a low price! 2,500
sheets of 60 gsm bond paper.

Cat.C21003 11x91" . $49.95
Cat. 21005 15x11" .... $67.95

Metall

Compatible with IBM* and
compatibles, and EGA Cards.
Why more?

Resolution: 640 x 350 dots

Dot pitch: .31mm

Display Format: 80 x 25 characters
Cat. X14514 ...... Normally $1,295

Our price $995

Resolution: 640 x 200 dots
Display Format: 80 x 25 characters
Display Colours: 16
Dot pitch: 39mm
Sync Horiz. Scan Freq: 15.75 KHz
Sync Vert. Scan Freq: 50Hz
Band Width: 18MHz

vo $695

Cat. X14520 ....

‘Revised and expanded edition)
-Peter Norton
The widely acclaimed guide to the
IBM PC's inner workings. The latest
edition now covers every model of
the IBM micro: PC, XT and AT, and
every version of DOS trom 1.1 to 3.0

B20080 tess $44.95

-Robert C. Brenner

Keep your IBM PC in top operating

condition with this handy reference

book. Inside you will find pages of

schematics, photos and block

cara to help you identify

problems. Simple instructions tell

you what's wrong and how to fix it

fast.

® Make most repairs with few or no
tools

® Quickly zero-in on a matfunctioning
component

@ Reduces downtime

@ Pays for itself many times over in
repair savings

@ Easy to understand circuit
diagrams.

The IBM PC Trouble Shooting &

Repair Guide will make even the

computer novice feel comfortable

with the complex world of electronic

trouble shooting. This fully illustrated

book is recommended for anyone

who uses an IBM PC.

Cat.B - $44.95

Stylish 20MHz, non-glare 12 inch
monitors available in green or amber
displays and featuring swivel base
that tilts forward and back and
swivels right to left!
Green Cat.X14506..Normally $235
Amber Cat.X14508..Normally $239
SPECIAL, ONLY $199

@ CCITT V21 300 baud full duplex
@ CCITT V23 1200/75

® Bell 103 300 Full duplex

ell 202 1200 Half duplex

uto answer, auto disconnect

ED display for Power, TX, RX,CD
\C power adaptor included

@ DB25 pin connector

© Telecom Approval N°\C83/37/1045

Cat. X19120 ........ $295
(SOFTWARE FOR VIATEL .. $95)

oz

-James R. Groff, Paul N. Weinberg
The exploding popularity of the
UNIX operating system is one of the
most important trends in computing
in the 1980's. UNIX is available on
hundreds of different computers,
ranging from personal computers to
mainframes and supercomputers.
Understanding UNIX offers an
overall perspective on UNIX,
including a discussion of where
UNIX fits in the worlds of computing,
business, and education. Individual
chapters address the UNIX structure,
file system, multiuser capability,
specific applications tools, and
more.

“A book that balances scope with
depth; comprehensiveness with
brevity." -Alan Kaplan

Gat vessiviwensss wanes $44.95

-Mitcnell Waite, David Fox

If you are learning programming or
have dabbled in the popular
language BASIC and wish to learn
the capabilities of Pascal, this book
is definitely written for you. Written
and illustrated with a touch of
humour, the informative text
describes Pascal program structure,
Pascal variables, Pascal procedures,
and many other features. There are
chapters on decision making
statements, numeric functions,
string functions, arrays and sets, and
much more. The eight appendices
present facts about the advantages
and disadvantages of Pascal,
components of a Pascal system,
interfacing assembly language
routines, and other useful

information,
Cat.B .. . $24.95

ROGRAMMERS
FNC ACLOPEDIA

-Bruce Brigham

The CP/M Programmer's
Encyclopedia is a time saving,
comprehensive reference for serious
CP/M users. Covering all the
commands and syntaxes for

CP/M 2.x and CP/M 3.0, this
encyclopedia gives you the
information you need in an
easy-to-use format especiall
designed for programmers. The
CP/M Programmer's Encyclopedia
is the only major compilation of
CP/M commands and syntaxes. If
you use CP/M extensively, you
should not be without this important
reference guide

Cat.B .. $39.95

-James S. Coan

Here's the key to using and enjoying
the Commodore 64 microcomputer.
A fast reading pure to computer
operation and BASIC programming
that is suitable for use at home or in
the classroom. The approach is
simple and direct.

CALEB) ssivsvcierinessavses $29.50

Practical tips and useful
programs tor IBM PC's from the
editors of PC World

Accollection of the best tips,
programs, and routines for IBM
computers from the popular
“Hands on” and *.* columns.
Covering both hardware and
software, the book is organised so
that you can quickly find information
on virtually everything you need to
know.

B20100 sccteninsannasin $34.95

-Thom Hogan

While other books will tell you how to
learn C, this one shows you how to
use it. It's a literal encyclopedia of the
information you'll need to get it to
work for you, efficiently and
effectively. Handy and well
organized, it gives you quick access
to the things you need, when you
need them, plus a clear definition of
C language with examples and
explanations of restrictions and
defaults. You won't find an approach
this understandable and objective

anywhere else.
820120 srenssniee GODS

Revised and expanded edition)
-Peter Norton
The widely acclaimed guide to the
1BM PC's inner workings. The latest
edition now covers every model of
the IBM micro: PC, XT and AT, and
every version of DOS from 1.1 to 3.0

BB008O 5 csivisrsransiaitts $44.95

rhe Pisin Paelish
WAINTEAANCE
REPUB GE iD
for EBM Persona
Computers

-Henry F. Beechhold

Even if you've never held a soldering
gun in your hand you'll appreciate
these clear, simple, witty
explanations of computer
electronics. With its lucid line
drawings and diagrams, this book
gives you expert instructions on
every fix-up and keep-up operation
for your IBM PC and its components
- DOS, peripherals, disk drive, and
the rest.

BPOOGO ssrinseinserescasiiars $53.95

SAMS

IBM PC Troubleshooting
& Repair Guide

BLESHOQ;
sone Fy,

-Robert C. Brenner
Keep your IBM PC in top operating
condition with this handy reference
book. Inside you will find pages of
schematics, photos and block
diagrams to help you identify
problems. Simple instructions tell
you what's wrong and how to fix it
ast.
@ Make most repairs with few or no
tools
Quickly zero-in on a malfunctioning
component
@ Reduces downtime
@ Pays for itself many times over in
repair savings
@ Easy to understand circuit
diagrams.
The IBM PC Trouble Shooting &
Repair Guide will make even the
computer novice feel comfortable
with the complex world of electronic
trouble shooting. This fully illustrated
book is recommended for anyone
who uses an IBM PC.
$44.95

Cat.B ..

-Jack Purdum

Learn at your own pace as this self
directed study guide takes you
through the basics and into advanced
areas of the C programming
language. The unique format allows
a to advance quickly or proceed
slowly. The book is divided into two
parts:

Questions: of varying degrees of
difficulty to guide beginners over the
rough spots and to challenge the
more experienced C programmers
Answers: that.include many complete
Programs for testing new functions
and for illustrating tips, traps,
techniques and short cuts.

GRUB ssansnsnosecnencsaean $37.95

-Winston D. Gayler

© Covers all Apple Il motherboard
and keyboard versions.

@ Helps you learn about
microcomputer hardware in
general and Apple II hardware in
detail.

@ Provides you with accurate
schematics and verified waveforms
to rely on for servicing and repair.

@ Explains the advanced concepts
of daisy chains, interrupts, direct
memory, access, and the ready
ine

@ Gives you many valuable hints for
successful interfacing.

® Contains tutorials on video
signals, memory IC's and the
6502 microprocessor, as well as
full explanations of advanced
concepts.

@ Each chapter contains an overview
for the beginner and a detailed
section for the more adventurous.

@ Ideal for students, technicians,
hobbyists, engineers, and others
who need Apple II technical
information.

Cats sccsiicvrainnnaaen $52.95

Mount your speakers at ear level on
four wall!!
eatures.
© Holds speakers up to 260mm deep
© Left/Right adjustment
p/Down adjustment
@ Includes mounting screws
© Nipping-screw pins hold speakers
firmly in place
@ Installation instructions

Cat. . $89.95

9 ntuZe
9. yanil hale Ming zo

We have a great range ot panel

meters at great prices!

Cat.No. Description Price
Q10500 MU45 0-1mA 12.50
Q10502 MU45 50-0/50UA_ 12.50
Q10504 MU45 0-100uA 12.50
Q10510 MU45 0-5A 12.50
Q10518 MU450-1A 12.50
Q10520 MU450-1A 12.50
Q10525 MU45 0-20V 12.50
Q10530 MUS2E 0-1A 14.50
Q10533 MUS2E 0-5A 14.50

Q10535 MU45 VU PMetre 14.95

Q10538 MU65 0-50uA 16.95
Q10540 MU65 0-1mA 16.95
Q10550 MU65 0-100uUA 16.95
Q10560 MU65 0-20V 16.95

All prices per box and include tax
8007 REVERSAL FILM

250 x 300mm (10 sheets) . $39.95
300 x 600mm (5 sheets) ... $54.95
8005 BLACK ALUMINIUM

250 x 300mm (10 sheets) . $69.95

300 x 600mm (5 sheets) ... $79.95
8009 BLUE ALUMINIUM

250 x 300mm (10 sheets) . $69.95
300 x 600mm (5 sheets) ... $79.95
8011 RED/WHITE

250 x 300mm (10 sheets) . $64.95
300 x 600mm (5 sheets) ... $74.95
8013 BLACK/YELLOW

250 x 300mm (10 sheets) . $64.95
300 x 600mm (5 sheets) $74.95
8015 BLACK/WHITE

250 x 300mm (10 sheets) . $64.95
300 x 600mm (5 sheets) ... $74.95
8016 BLUE/WHITE

250 x 300mm (10 sheets) . $64.95
300 x 600mm (5 sheets) ... $74.95
8018 GREEN/WHITE

250 x 300mm (10 sheets) . $64.95
300 x 600mm (5 sheets) ... $74.95

The WTCPN Features:

@ Power Unit 240 V AC

@ Temperature controlled iron,
24V AC

® Flexible silicon lead for ease of
use

© Can be left on without fear of

damaged tips!
The best is always worth having.
GatiTIZ500 cascccsssore R.R.P. $149

SPECIAL, ONLY $129

These superb rack mount cabinets

will give your projects a real

professional appearance!

Just look at these features...

@ All dimensions conform to the
International Standard

@ All aluminium construction

@ Choice of black or natural finish

© Deluxe brush finish anodised front
panel

@ Removeable top and bottom lid

@ Ventilated lid

A = Internal Height mm
B = Rear Width mm
C = Depth mm

A B C Finish Cat.No. Price
38 430 254 Natural H10401 $49.50
82 430 254 Natural H10402 $59.50

126 430 254 Natural H10403 $69.50
38 430254 Black H10411 $59.95
82.430 254 Black H10412 $69.95

126 430 254 Black 10413 $79.95

— a!

Diecast boxes are excellent for

FF shielding, and strength.

Screws are provided with each box
H11451 100x 50x 25mm . $ 5.95
H11452110x60x30mm . $ 6.50
H11453 120x65x 40mm . $ 6.95

H11461 120x94x53mm . $11.50
H11462 188 x 120 x 78mm... $13.50
H11464 188 x 188 x 64mm... $29.50

Why pay more?
Cat.P11000 100 holes ..... $2.75
Cat.P11005 640 holes ....... $10.75

Cat.P11007 640+ 100 holes $13.00
Cat.P11009 840+ 200 holes $17.50
Cat.P11010 1280+ 100 holes $19.95
Cat.P11011 1280+300 holes $32.50
Cat.F 11012 1280+ 400 holes $36.75
Cat.P11015 1920+500 holes $57.50
Cat.P11018 2560+ 700 holes $64.95

Compact P.I.R. with adjustable

comer or wall mounting bracket,

dual pyroelectric infra red sensing

element gives a coverage 2 x 14

zones 2m high and 10m wide

© Sensitivity adjustment control

® Detecting range 12-15 metres at
90 degrees

© Detecting zones 9 long (up),
5 short (down)

@ LED indicator for walk test. (can be
disabled)

@ Shielded against RF interference

@ Relay output NC or NO at 30V
(AC-DC) 0.5A max.

@ Integral NC tamper switch

@ Operating voltage 10.5 - 16V DC

© Current 20mA with LED 25mA

Cat. $7722? .... $145

@ Telephone type digital keypad.

© Four digit, changeable code.

@ Over 5000 possible combinations.

@ Power consumption: 5mA standby,
50mA alarm.

@ Two sector LED and 1 arm LED.

@ Wrong number lockout.

@ 12V DC operation

@ Relay output.

@ Panic button.

@ Normally open tamper switch.

@ Dimensions: 145 x 100 x 37mm

@ ACP3 compatible.

Cat. A13014 .......... R.R.P. $79.95
SPECIAL, ONLY $69.95

Cat. No. Description
W11251 13/.12 TND BLK
W11252 13/.12 TLD BROWN
W11253 13/.12 TLD ORANGE
W11254 13/.12 TLD YELLOW
W11255 13/.12 TLD GREEN
W11256 13/.12 TLD BLUE
W11257 13/.12 TLD WHITE
PRICES PER 100 METRE ROLL

1-9 10+
$5.95 $5.00
$5.35 $4.50

W11260 14/.20 RED
W11261 14/.20 BLACK
W11265 14/.20 BLUE
W11268 14/.20 WHITE

PRICES PER 100 METRE ROLL
1-9 10+
$12.00 $10.00
$10.80 $9.00
W11270 24/,20 RED
W11272 24/.20 BLACK
W11274 24/.20 GREEN

PRICES PER 100 METRE ROLL
1-9 10+
$14.00 $12.00
$12.60 $10.80
W11280 32/.2 BROWN
W11282 32/.2 BLUE

PRICES PER 100 METRE ROLL
1-9 10+
$20.00 $18.00
$18.00 $16.20

Leakproof and in 3 convenient
sizes, these long service life
batteries are ideal for burgular
systems, emergency lighting or as a
computer backup power supply.
Ideal for many power needs.

Cat. $15029 12V 1.2 AH $17.50
Cat. 15031 12V 2.6 AH $32.50
Cat. $15033 12V 4.5 AH $39.50

@ Female to Female.

© Saves modifying or replacing

non-mating Centronics cables.

@ All 36 pins wired straight through

Cat. X15663 Male to Male

Cat. X15661 Male to Female

Cat. X15664 Female to Female
Normally $33.95,
Only $24.95

© Ultra Low Power
© Separately Addressable
Annunciator

@ 15mm Digits

e Banagap Reference
A low profile LCD DPM with a range
of useful symbols as shown. The
DPM 200 features 15mm 31/2 digit
display, and ultra low current
consumption and a bandgap
reference for high stability. It also
features Auto-zero, Auto-polarity,
200mV fsd. It may be used in single-
ended, differential or ratiometric
modes. The fsd can be easily
changed by the user to indicate any
other units. The decimal points and
symbols can all be driven from an
internal source. Wide supply and
symbols can all be driven from an
internal source. Wide supply rail
(5-15V DC) with a variable threshold
low battery warning indicator.
Supplied with mounting clips and
comprehensive data sheet.
SPECIFICATIONS:
Accuracy: 0.1% +—1 digit
Linearity: + —1 digit
Samplesiaece 3

‘emp. Stal : 50 ppm typical
Temp. Rangeso - 50°C ie
Supply Voltage: 5 - 15V DC
Supply Current: 50uA typical
Max DC Input Volts: + —20V

Cat. Q15510 $99.95

This superb 3 way speaker kit
competes with systems that cost
2-3 times the cost of these units!
(which may even be using VIFA
drivers etc.) Never before has it
been possible to get such

ex lonal value in kit speakers!
Call in personally and compare
for yourself!

The system comprises...

2x D19 dome tweeters

2x D75 dome midrange

2x P25 woofers

2x pre-built quality crossovers

The cabinet kit consists of 2 knock-
down boxes in beautiful black grain
look with silver baffles, speaker
cloth, innerbond, grill clips, speaker
terminals, screws and ports.

D19 DOME TWEETER SPEAKER
SPECIFICATIONS
Nominal Impedance: 8 ohms
Frequency Range: 2.5 - 20kHz
Free Air Resonance: 1,700Hz
Sensitivity 1W at 1m: 89dB
Nominal Power: 80 Watts

(fo: 5,000Hz, 12dB/oct)
Voice Coil Diameter: 19mm
Voice Coil Resistance: 6.20hms
Moving Mass: 0.2 grams
Weight: 0.28kg

D75 DOME MIDRANGE
SPECIFICATIONS:
Nominal Impedance: 8 ohms
Frequency Range: 350 - 5,000Hz
Free Air Resonance: 300Hz
Sensitivity (1W at 1m): 91dB
Nominal Power: 80 Watts

(fo: 500Hz, 12dB/oct)
Voice Coil Diameter: 75mm
Voice Coil Resistance: 7.20ohms
Moving Mass (incl. air): 3.6 grams
Weight: 0.65kg

P25 WOOFER SPECIFICATIONS:
Nominal Impedance: 8 ohms
Frequency Range: 25 - 3,000Hz
Free Air Resonance: 25Hz
Operating Power: 5 watts
Sensitivity (1W at 1m): 89dB
Nominal Power: 60 Watts
Music Power: 100 Watts
Voice Coil Diameter: 40mm
Voice Coil Resistance: 5.70ohms
moving Mase (incl. air): 44 grams
Thiele/Small Parameters:

Qm: 3.15

Qe: 0.46

Qt: 0.40

Vas; 180:1
Weight: 1.95kg

Complete Kit Cat.k16030 $1,199
Speaker Kit Cat.K16031 . $949
Cabinet Kit Cat.K16032 .. $349

Made by Piezo (Azden) of Japan,
this device will turn any microphone
fitted with a Cannon Type male
socket into a wireless microphone.
The receiver will plug into any
6.35mm microphone input. Both
transmitter and receiver can be
tuned from 76 - 81MHz.
Freq. Response: 50 - 16kHz
Tunable: 76 - 81MHz
Field Strength:
Transmitter 10uV/100 metres
Receiver 15mV (100%)
Battery: Transmitter LR44 (1.5V)
Receiver 3 x UM4 (4.5V)
Instructions: Japanese (English
not available!)
Cat. A10520 R.R.P. $199
Our price, only $189

This exciting new ker kit,
designed by David Tillbrook (a
name synonymous with brilliant
design and performance) uses
VIFA's high perfomance drivers
from Denmark. You will save
around $800 when you hear what
you get from this system when
compared to something you buy
off the shelf with similar
characteristics. Call in personally
and compare for yourself!
The system comprises...
2x P21 Polycone 8” woofers
2 x D25T Ferrofluid cooled dome
tweeters with Polymer diaphrams
2 pre-built quality crossovers
The cabinet kit consists of 2 knock-
down boxes in beautiful black grain
look with silver baffles, speaker
cloth, innerbond, grill clips, speaker
terminals, screws and ports.

D25T SPEAKER SPECIFICATIONS
Nominal Impedance: 6 ohms
Frequency Range: 2 - 24kHz

Free Air Resonance: 1500Hz
Operating Power: 3.2 watts
Sensitivity (1W at 1m): 90dB
Nominal Power: 90 Watts

Voice Coil Dia

Air Gap Height: 2mm

Voice Coil
Moving M: 0.3
Weight: 0.53kg

P21 WOOFER SPECIFICATIONS:
Nominal Impedance: 8 ohms
Frequency Range: 26 - 4,000Hz
Free Air Resonance: 33Hz
Operating Power: 2.5 watts
Sensitivity (1W at 1m): 92dB
Nominal Power: 60 Watts
Voice Coil Diameter: 40mm
tore Coil Resistance: 5.8ohms
loving Mass: 20 grams
ThieleSmail Parameters: Qm: 2.4
Qe: 0.41
Qt: 0.35
Vas: 80:1

Weight: 1.65kg

Complete Kit Cat.K16020... $799
Speaker Kit Cat.K16021 .. $649
Cabinet Kit Cat.K16022 .. $209

Tuneable: 92 - 104MHz

Freq. Response: 50 - 15kHz
Range: Over 300 feet in open field
Modulation: FM

Power Source: 9V Battery

Type: Electret Condenser.
Dimensions: 185 x 27 x 38mm
Weight: 160 grams

Cat. A10450 .. $19.95

MICROPHONE SPECIFICATIONS:

Transmitting Frequency: 37.1MHz

Transmitting System: crystal
oscillation

Microphone: Electret condenser

Power Supply: 9V battery

Range: 300 feet in open field

Dimensions: 185 x 27 x 38mm

Weight: 160 grams

RECIEVER SPECIFICATIONS:

Recieving Freq: 37.1MHz

Output Level: 30mV (maximum)

Recieving System: Super
heterodyne crystal oscillation

Power Supply: 9V Battery or 9V DC
power adapter.

Volume control

Tuning LED

Dimensions: 115 x 32 x 44mm

Weight: 220 grams

Cat. A10452 R.R.P. $113

Our price, $99

udio Audio Audio

The new Vifa/EA 60+60
loudspeaker kit has been designed
to complstely out perform any
similarly priced speakers. This is a
2-way design incorporating drivers
which give a deeper, more natural
bass response and 19mm soft-dome
ferro fluid cooled tweeters which
provide clear, uncoloured sound
reproduction

These Vifa drivers are identical to the
ones used in such fine speakers as
Mission, Rogers, Bang & Olufsen,
Monitor Audio and Haybrook just to
name afew. Some of which cost well
over $1,000 a pair!

The dividing network is of the highest
quality and produce no inherent
sound characteristics of their own;
they simply act as passive devices
which accurately distribute the
frequency range between both
drivers in each speaker.

The fully enclosed acoustic
suspension cabinets are easily
assembled. All you need are normal
household tools and a couple of
hours and you've built yourself the
finest pair of speakers in their class!

D19 TWEETER SPECIFICATIONS:
Nominal Im ice: 8 ohms
Frequency Range: 2.5 - 20KHz
Free Air Resonance: 1,700Hz
Sensitivity 1W at 1m: 89dB
Nominal Power: 80 Watts

(fo: 5,000Hz, 12dB/oct)
Voice Coil Diameter: 19mm
Voice Coil Resistance: 6.2 ohms
Moving Mass: 0.2 grams
Weight: 0.28kg
Sate ClOsO ssiscscscssssscaises $38

C20 WOOFER SPECIFICATIONS:
Nominal Im) ce: 8 ohms
Frequency Range: 35 - 6,000Hz
Resonance Frequency: 39Hz
Sensitivity 1W at 1m: 90dB
Nominal Power: 50 Watts
(12dB/oct)
Voice Coil Diameter: 25mm
Voice Coil Resistance: 5.5 ohms
Moving Mass: 15 grams
Cat. C10322 .. sess $89

Cat. K86092 (speakers only) $379
Cat. K86091 (complete kit) ... $449

This month we are offering 20% off
these prices! But, you'd better be
quick as this offer is limited.

Description Cat.No. Price
AD01610T8 (C12030) .... $24.95
AD02160SQ8 (C12040) . $69.95
AD80652W8 (C12042) .. $69.95
ADO70620M8 (C12045) . $69.95
AD12250W8 (C12050) .. $129.00

Acompletely portable system, sets
up anywhere in seconds. Inputs for
microphone, electronic organ and
cassette players. Variable echo
makes this an ideal unit for buskers
and budding singers.
SPECIFICATIONS:
Output power: 1W RMS, 2W max
Frequency Response: 100-15kHz
Speaker: 5” full range, 4 ohms
Echo Time: Variable 5-52m/sec
Power Source: 6 x "D" size batteries
(position for power adaptor also)
Size: 280(H) x 120(W) x 180(D)mm
Weight: 1.3kg
Cat. A12022 $89.95

The worlds best headphones are
now available from Rod Irving
Electronics!! 3 models to choose
from, other models are available
on request! (Phone Tony DiPaolo
on (03) 543 2166)

The HD40 is feather light, at just 60g!

This HiFi stereo headphone is

uncommonly convenient to use. Its

systems can be rotated so it can fit

into any drawer. It is also available

as a TV headphone.

SPECIFICATIONS:

Frequency Range: 22 - 18,000Hz

Impedance: 6000hm

Distortion Factor: Approx. 1.5%;
pressure on ear; approx. 1.3N

Weight: Approx. 60g

Length of lead: 3 metres

Cat. A10815 cece $49.95

The HD 410 SL embodies all the
advantages of the new "Slim-line”
concept: brilliant sound character-
istics with an optimum of sound
volume combined with high wearer

comfort.

SPECIFICATIONS:

Frequency Range: 20 - 18,000Hz

Impedance: 6000hm

Distortion Factor: Less than 1%;
pressure on ear; approx. 2.5 N

Weight: Approx. 829

Length of lead: 3 metres

Cat. A10518 .. . $74.95

The HD 540 reference headphones
are open dynamic stereo
headphones. They are among the
best ever made. Designed according
to latest findings in acoustics, their
reproduction is of extraordinary
transparency and the highest
transients fidelity. The test with a
CD player shows: their acoustic
properties are outstanding. The ear
cushions play a major role. They
provide a completely resonance-free
treble reproduction up to 25 KHz and
assure an impressively clear bass
reproduction down to 16 Hz.
SPECIFICATIONS:
Frequency Range: 16 - 25,000Hz
Impedance: 600ohm per capsule
Harmonic Distortion Factor:

Less than 0.4%
Contact Pressure: Approx. 3N
Weight: Approx. 250g
Length of lead: 3 metres

Cat. A10519 $199

Mylar diaphragm
SPECIFICATIONS:
Sensitivity: 96dB

Frequency Response: 2-20 kHz
Impedance: 8 ohms

Power RMS: 15 watts RMS
Magnet Weight: 5.4cz.

Size: 96mm diameter

Cat. C10234 once $10.95

Mylar diaphragm, aluminium voice
i!

coi

SPECIFICATIONS:

Sensitivity: 95dB

Frequency Response: 1.5-20 kHz
Impedance: 8 ohms

Power RMS: 10 watts RMS
Magnet Weight: 2.50z.

Cat C1022" spriasacrecnreves $8.95

Sealed back, foam edge, black
cone, silver dust cap.
SPECIFICATIONS:
Sensitivity: 98dB
Frequency Response: 500-8 kHz
Impedance: 8 ohms
Power RMS: 10 watts RMS
Magnet Weight: 5.40z.

$12.95

Cat. C10230

Foam edge, black cone, black
whizzer cone

SPECIFICATIONS:

Sensitivity: 89dB

Frequency Response: 60-15 kHz
Impedance: 8 ohms

Power RMS: 10 watts RMS
Magnet Weight: 5.302.

Cat, C10222 ...sccsressson '$

Foam edge, black cone, black
whizzer cone

SPECIFICATIONS:

Sensitivity: 98dB

Frequency Response: 45-16 kHz
Impedance: 8 ohms

Power RMS: 30 watts RMS
Magnet Weight: 1302.
Cat. C10224 ooo cece $23.95

Cloth edge, dark grey cone, rubber
mounting seal, cloth dust cap.
SPECIFICATIONS:

Sensitivity: 90dB

Frequency Response: 60-4 kHz
Impedance: 8 ohms

Power RMS: 50 watts RMS
Magnet Weight: 200z

Cat. C10226 orcs $34.95

Cloth edge, dark grey cone, rubber
mounting seal, cloth dust cap.
SPECIFICATIONS:

Sensitivity: 93dB

Frequency Response: 50-2.5 kHz
Impedance: 8 ohms

Power RMS: 100 watts RMS
Magnet Weight: 300z.

Cat. C10228 ....sscseccssseee $59.95

Cloth edge, dark grey cone, rubber
mounting seal, cloth dust cap.
SPECIFICATIONS:

Sensitivity: 97dB

Frequency Response: 28-4 kHz
Impedance: 8 ohms

Power RMS: 50 watts RMS
Magnet Weight: 300z

Cat. C10229 o.cceccccs, $69.95

VISA

Satellite television
in Australia

A practical guide to the reception of satellite television
in Australia and the Pacific

AVE YOU EVER wondered,

as you drove past your local

TV station, what that large
dish was doing, pointing skywards?
Chances are that it is a vital part of a
satellite television earth station. Those
dishes are just part of the very large
investment that the major television
networks have made in satellite broad-
casting. But the game is not closed to
the small players.

Recent advances in low noise ampli-
fier technology have brought the world
of satellite television into the backyards
of hundreds of thousands of enthusiasts
worldwide and, with it, access to inter-
national television. Now these advances
can be used by enthusiasts in Australia.

To explain how satellite television
came about requires a brief look at his-
tory. The first man-made satellite was
Russia’s Sputnik launched in 1957. It
bleeped a Morse code message around
the Earth, proving that reception from
space was possible.

Subsequently, the US Air Force
launched SCORE in December 1958
which broadcast a recorded message of
Christmas greetings from the President
of the USA to all who cared to listen.

This was the dawn of satellite com-
munications.

by GARRY CRAPP VK2YBX/T

By 1963, space technology and pro-
pulsion systems had progressed to the
stage where satellites could be launched
into geosynchronous orbit rather than a
low orbit which required continuous an-
tenna tracking. Geosynchronous, (or
geostationary) satellites orbit directly
over the equator and their angular ve-
locity is identical to that of the Earth —
hence the position of a reception an-
tenna remains fixed.

Intelsat

SYNCOM, which was launched in
1963, provided a single TV channel (or
50 telephone circuits) between North
America and Europe and allowed real-
time television transmissions. By 1965,
19 countries had realised the importance
of such communications and formed an
organisation called Intelsat which would
fund and launch a series of satellites.
Today, over 100 nations belong to the
Intelsat network.

This network consists of 12 satellites
located in three separate groups. These
groups are located over the equator in
the Pacific, the Indian Ocean, and be-
tween Africa and South America (At-
lantic). Each satellite group has one pri-
mary and one secondary satellite al-

These pictures were received in Australia via the Intelsat network on typical equipment as
described in this article.

26 ELECTRONICS Australia, June 1987

though heavy traffic in the Atlantic and
Indian Ocean areas has required addi-
tional satellites in both these groups.

In 1971, Intelsat agreed that identical
frequency satellites should be spaced
over the equator in increments of four
to five degrees. This allows reception of
the desired satellite without adjacent
channel interference. Of course, many
countries have a far greater need for
satellite communications than Intelsat
can provide. These include Australia,
the USA, Canada, Russia, India, Indo-
nesia, Saudi Arabia, Mexico, Japan and
many others.

In each of these countries, reception
of satellite television is possible with
relatively inexpensive equipment provid-
ing not only a basis for cultural ex-
change, but an ideal vehicle for hands-
on experience of satellite reception.

Basic components

The basic components of a satellite
television reception system or TVRO
(TV Receive Only) system, are as fol-
lows:

(1). The Antenna: This needs to col-
lect as much signal energy as possible.
The most suitable type for TVRO use is
the parabolic dish antenna, which pro:
vides the optimum size/gain ratio.

The most important feature of the
dish, apart from size (bigger is better) is
the accuracy of the surface. It is impor-
tant that the surface conform as closely
as possible to a true parabolic curve. A
variation of more than 3mm from a true
parabolic surface can cause a significant
reduction in signal gain.

(2). The Feedhorn: This collects the
signal focussed upon it from the surface
of the dish and, through an_ integral
waveguide, presents the signal to the
low noise amplifier (LNA). The most
popular and widely used type is the
prime focus feedhorn, so called because

This 3.5-metre dish is available from Dick Smith Electronics

it is placed at the focal point of the
dish.

The mouth of a feedhorn may be sur-
rounded by a series of concentric rings
called scalar rings. These are used to
help direct microwave signals in the
general area of the feedhorn into the
opening of the waveguide.

Most of the energy picked up by a
typical feedhorn comes from the inner
three quarters of the surface area of the
dish. The advantage of the scalar ring
feedhorn is that it gathers signals all the
way to the perimeter of the dish and
thus increases the overall gain of the
system. As an aside, some parabolic

dishes have their outer curvature modi-
fied to compensate for the characteris-
tics of a particular feedhorn and so opti-
mise the gain in that way.

(3). Low Noise Amplifier; The signal
from the feedhorn goes via a waveguide
to a small antenna probe which is nor-
mally only about 12mm long because of
the short wavelengths involved.

The antenna probe is cut so that it is
resonant across the band of frequencies
being used. Its length and shape are
critical because it must favour signals
over wideband noise. From the antenna
probe, the signal is coupled to the low
noise amplifier (LNA) which uses Gal-

lium Arsenide (GaAs) Fets to provide
an extremely low noise figure. LNAs
are rated in Kelvins (formerly called de-
grees Kelvin) and the lower the Kelvin
rating, the lower the noise contributed
by the LNA to the overall receiving sys-
tem.

(4). The Down-converter: Basically
the down-converter is equivalent to the
front end of a superheterodyne receiver
and consists of a mixer and a local oscil-
lator. The output of that mixer/local os-
cillator arrangement is an intermediate
frequency (IF) which, for most TVRO
systems, is 70MHz.

In a superhet receiver, the mixer and
local oscillator circuits are tuned simul-
taneously so that the IF is always con-
stant. Since the down-converter is lo-
cated outdoors, close to the LNA, it is
tuned remotely by a variable DC volt-
age. This is furnished by the satellite re-
ceiver and varies between 4 and 14 volts
DC in most cases. The receiver has a
tuning dial permitting selection of any
transponder on a satellite.

A further development in down-con-
verter technology involves the combina-
tion of both the low noise amplifier and
the down-converter at the dish. This
combination is called a low noise con-
verter (LNC) and has several advan-
tages. The need for a cable link be-
tween the LNA and the down-converter
is eliminated, and the two units are
mounted in a single waterproof enclo-
sure. As a result, installation is consid-
erably simplified.

The latest down-converter technology
is called Blockdown conversion. This
utilises an LNA/down-converter combi-
nation called an LNB. In this approach,
all the channels presented at the input
of the down converter are handled si-
multaneously and a complete block of
frequencies is fed to the satellite receiv-
er. This technique is favoured by hotels,
motels and high-rise apartment houses
as a way of permitting individual chan-
nel selection whilst minimising the re-

This block diagram shows the basic equipment needed for an Intelsat home earth station. Note that the monitor used must be compatible
with the signal received from the satellite (eg, NISC for the American Armed Forces Radio & TV Service, PAL for Australian/NZ feeds,
SECAM for Gorizont).

ELECTRONICS Australia, June 1987 27

good signal levels. In Australia, the highest footprint on trans-

ponders, using the vidiplex technique approximates 17dBw, .

which is very weak indeed.

To display both frames separately, a far more economical
technique is available even though it is in black and white. By
obtaining a black and white television receiver and rotating
the picture tube yoke 90 degrees, both frames can be dis-
played separately, vertically stacked, once the vertical hold is
adjusted.

Microwave power level
and space loss

The ground to satellite signal path in the 6GHz range re-
quires substantial transmitter power between 1kW to 3kW plus
large antenna gains of 50 to 60dB to saturate the input of the
satellite with high quality noise free signals. Like any relay sta-
tion, the signal quality returning to Earth is only as good as
that initially transmitted to the satellite. On the uplink path
free space loss approximates 198dB. Our primary interest is in
the downlink since this is where we can participate.

The downlink frequency band limits are 3.7GHz to 4.2GHz.
This is often a shared band with terrestrial microwave links so
interference may occur at some sites. This is the first thing to
check before installing a TVRO system. The satellite’s signal
is contained within a 35MHz wide frequency band. The video
signal is FM and the audio signal is FM, being transmitted as a
sub-carrier between 5 and 8MHz. Because this is an FM sys-
tem, one important factor must be considered that is not part
of a normal AM terrestrial television transmission.

The most important factor is called the FM threshold. On
any FM receiver, when an FM signal reaches full quieting, all
background noise is gone. As long as the signal stays above
the threshold of noise, you have no way of judging without
complicated test equipment how close you really are to the
noise since, in full quieting, there is virtually no noise. The
signal may be far above that required for full quieting or it
may only be marginally above the level required for full quiet-
ing.

This means that if the frequency modulated satellite signal
can be maintained just above the noise threshold and, if the
satellite signal is very stable, we can get by with a low margin
receive system. To normal visual inspection, this would give
the same apparent picture quality as a signal that is many dB
stronger than full quieting.

Even with the weak signal provided by Gorizont and Intel-
sat satellites in Australia, it is possible to achieve a signal level
marginally above threshold by adjusting the IF bandwidth and
using “threshold extension techniques” in the receiver.

Conclusion

The science of satellite reception is a very exacting one at its
present stage of development. One of the mental hurdles you
must adjust to, is thinking in terms of 0.1dB or 0.5dB differ-
ences as being substantial.

As previously mentioned the down link path loss approxi-
mates 200dB and is proportional to the distance squared be-
tween the Earth and the satellite. This Earth-to-satellite dis-
tance is about 37,000km.

Because the satellite transponder power is limited by battery
and solar cell capacity to 5 watts DC input power (typically),
and because of the tremendous distance involved, the signal
reaching the Earth has an approximate signal strength of 0.5 x
10° watts. This is less than the thermal noise level present at
the ground. @

One
Machine
Workshop

A multi-function
machine tool

A heavy-duty professional unit which Turns, Mills, Screw Cuts,

Grinds, Drills, Slots, Cuts Gears ... and more. All cutters, slot

drills, etc., are Standard Equipment. Workable diameter.300mm.

Max. Length of work 550mm. Driven by 2-speed heavy-duty

electric motor. A real workhorse at an economical price. Built to

i Ordinance Factory Standards. Available 240 volt 1
ase.

(VIC)

129-131 McEwan Road,
West Heideliberg. 3081.
Ph: (03) 459 6011
(NSW)

25 Cosgrove Road,
PTY. LTO. Enfield. 2136. ,
Ph: (02) 642 5363
el Dal = — a re =a feel a ial — ee
[Please send me further information on the H11-1A Multi-function
Machine Tool without obligation.

| name

ELECTRONICS Australia, June 1987 29

yy Yy 45 A'BECKETT STREET CITY

Yi py TELEPHONE 663 2030

Sensational at $499

Jaycar is proud to announce that we have made a SCOOP
PURCHASE of genuine VIATEL terminals WITH 14" COLOUR
MONITOR at an unbelievable pricell

We can pass ENORMOUS SAVINGS on to you as a result! Here's
the story.

A large National Electronic goods rental company came to us. They
She had a quantity of professional (European made) "Viatel* terminals
which they wanted to sell. They wanted to sell them because they
had a new terminal that had an integrated monitor and larger page
memory storage. There is nothing wrong with the ones offered, they
said. They were between 3 & 5 years old and had been in typical
office environments, were very clean and in good condition and had
been in constant service contract. They were very reliable anyway
however. The units sold for over $1,900 new but the batch being
offered was ex-rental.

Well, we bought them, and they ARE in very good condition! Now,
thru JAYCAR, you can own a fully dedicated VIATEL TERMINAL at
a FRACTION OF THE PRICE of new or equivalent units! As far as we
can tell the nearest new commercial unit costs $1,400, so at $499
you are making a massive saving (although the goods offered are
NOT new).

RGB MONITOR. Such is the quality of this system the monitor has
RGB input. RGB signals from a suitable computer can be connected
to the monitor so that it can double as a high res COLOUR computer
monitorl With a composite to RGB adaptor you can use virtually any
computer!

VIATEL ADAPTOR. The adaptor is professionally made by Philips
& INCLUDES an inbuilt modem to Viatel standard (1200/78). It
features:

- Detachable remote keypad

- Keylock ON/OFF switch

- Centronics type printer port Ring

- Telecom approved (C82/39/489)

Taps tcor dort (02) 747 2022

- Full keyboard port and ask for

- Instructions “Mr Viatel"

for full details!

QUANTITIES LIMITED! We DO NOT have a warehouse full of these and we do expect them to sell FAST| PLEASE f you do want one of these GET IN EARLY. Stock will be sold strictly to
the first buyers.

PERSONAL SHOPPERS ONLY. Stock is limited to personal shoppers only. (At this price we do not have time to pack them in a box!)

WARRANTY. Because the goods are ex-rental no warranty applies. We do, however, check each unit out for operation BEFORE they leave the store. The rental company are happy to
provide a SERVICE CONTRACT for the goods if you wish. We also can provide service manual sets for $20 extra. We must emphasise that this product has proven to be very reliable but
the goods are sold as is.

12 VOLT 15 AMP SPST RELAY
- NORMALLY OPEN CONTACT -

Japanese made, chassis mount with
quick connect terminals.

Can be used for 240 volt applications.
Silver alloy contacts.

1 amp 400V quenching diode
fitted across coil.

Data sheet supplied.

Cat. SY-4048

$5.00

The AEM 6000 amplifier system kit is NOW AVAILABLE ex-stock.

240 watts RMS per channel of pure power. $998 gets you the complete
kit, nothing else to buy.

Cat. KM-3020

ULIRA FIDELITY PREAMP

Ref: AEM May/June 1987
Here's the low-cost way to get on the air with radioteletype (RTTY). This encoder teams up
with the ever popular AEM 3500 Listening Post kit (Cat. KM-3015 $39.95) to make a complete

transmit/receive tone decoder/encoder. Join the ranks of the thousands of amateurs around the

world using the fascinating RTTY model Designed to connect in line between your AEM3500

Listening Post and your computer. The Jaycar kit comes complete with with case, Scotchcal front
panel and connection hardware for "Listening Post". See AEM for software info.

al $59.95

100 WATTS INTO 4 OHMS/50 WATIS INTO 8 OHMS!
Ref: AEM January 1987

A genuine low cost power amp “slave' module. Keeps costs down by
having power supply filter caps on board. All that is required to make
module operational is +30 - 40V (DC unfiltered), a signal source and a
load. Works well with PA line transformers too. All board parts supplied
including jig drilled heatsink bracket.

Cat. KM-3050

= Ref: EA May 1987
This simple project connects directly to the battery in your car. It will
indicate under-normal - or overcharging via a bar display of yellow
fife oeleen retrospect Me ,
Cat. KA-1684 Module can be used on its own or ganaged to equalise a whole system. Parametric equalisers tune
. around a centre frequency reducing the number of units required in a signal line (reducing distortion)
over the more normal "grahic" equalisers.
The Jaycar kit is supplied with all board components including pots, knobs, switch and TLO71 IC.
¥ SEE THE 1987 JAYCAR CATALOGUE FOR SPECIFICATIONS
at. KE-4724

Ref: ETI July 1980
Ref: EA Dec 1983

We're ae ee og at a bargain pricel W E R E $44.95
(Hall-etfect contactless J U N E ON LY
carkiscss | SAVE $10! $

34.95

Ref: EA September 1984
That's right for JUNE ONLY you can grab the best model train controller of them all for Ref: EA June 1986
$20.00 off. Avery handy project, but slashed this monthil .

NORMALLY $109.95 THIS MONTH $89.95 | NORMALLY $18.50
i THIS MONTH $12.00!!!

Cat. KA-1527

‘ae Electronics Australia

pharenll

vero VIDEO AMPLIFIER

Ref: EA June 1986
A great idea but we need the space for new kits! Probably too expensive
quite frankly at $55.00 but NOT at $25.00 - over 50% OFF. UNBELIEVABLE!

mee = SAVE 55%l! - WOW!!

CLL

@Meéell

GET A BARGAIN WHILE YOU CANI

Jaycar is discounting Its two ioniser kits. We are only doing this because we have
purchased some built units from bankrupt stock at very low prices. It would cost us
in components for these kits, more next time than we are paying for current distress
stock built up products.

We have sold thousands of ioniser kits over the years and they are still popular.
Now is your chance to grab a bargain!

Cat. KJ-6510 SHORT FORM (no case)

NORMALLY $27.50
THIS MONTH $13.50!!

SEND A LARGE SAE AND $1.00
FOR THE 1987 JAYCAR 116
PAGE CATALOGUE FULL
OF ELECTRONIC PRODUCTS
FOR THE HOBBYIST

The EDU-LINK kit is a fibre optic evaulation system consisting of TTL compatible
transmitter board IR LED, 1 metre of fibre optic cable, photodiode and TTL compatible
receiver board. The fibre optic connectors are also included. Manual includes instructions,
theory and tutorial.

DIRECT IMPORT - YOU SAVE HEAPSI $49 95
Cat. KJ-6520 ‘i

The ideal unit to add to an alarm system. IR units
such as this unit do not respond to non-heat
tadiating objects - even the cat is unlikely to

trip this unit. When a human being passes the lens
the unit will selectively pick up IR radiation and
then not. A series of pulses are then sent to a
detector unit.

FEATURES:

12V DC powered

Double sensor
Computerised OC to lower
failure rate

Built-in test lamp

Alarm output SPST 30V DC
@ 1 amp

Cat. LA-5017

$109

Brand new ‘smart’ modem from an
Aussie leader. Has full auto
recognition of outgoing and
incoming calls. Permanently
connected to your phone and
computer. High speed 1200/1200
(V22), Bell 212 option is available
that can be fitted internally.
300/300, 1200/75, V21/V23

Cat. XC-4832

$499.00

V21/V22V23 (1200/1200)
Option fitted
Cat. XC-4834

$699.00

Full specifications in the Jaycar
1987 Catalogue - available for $1
from all stores or via mail (included
large SAE)

Cat. KJ-6511 FULL IONISER KIT

NORMALLY $49.50
THIS MONTH $29.50
SAVE $20.00 cuantiies strictly limited on both!)

45 A'BECKETT ST.,

CITY
TELEPHONE

663 2030

(Photo shows KJ-6511 with lid removed)

Genuine Mallory 'Sonalert’.

This device mounts near the rear of any
12V vehicle. When +12V Is connected
(i.e, from reverse gear switch) it will give
that familiar “beep-beep" noise. Simple
panel mount fixing. (Operates 4-28V)
69d0BA min - 80dBA max.
Cat. AB-3442

A BARGAIN AT ONLY

These beautifully crafted rack cabinets will give your equipment a real 1st class
appearance. All aluminium construction. Removable top and bottom panels. Natural or
black finish. All dimensions conform to the International standard. Ventilated lid. Deluxe
brush finish anodised front panel. Individually cartoned. Supplied in flat pack form and
easily assembled in a few minutes.

SIDE ELEVATION: D = 254mm; C (internal chassis height); B (mounting bolt centres.

Finish A B Cc Each +5
Cat.HB-5411 Natural 44 34 38 $65.00 $62.00
Cat. HB-5413 Natural 88 57 82 $75.00 $71.00
Cat.HB-5415 Natural 182 89 126 $85.00 $80.00
Cat. HB-5410 Black 44 34 38 $65.00 $62.00
Cat. HB-5412 Black 88 57 82 $75.00 $71.00
Cat. HB-5414 Black 192 89 126 $85.00 $80.00

Beware of other rack cabinets that do not conform to International Rack sizing.

we nave once again made a scoop purchase of a partially assembled fan speed
controller that was part of a well known Australian made product.

The controller consists of a PCB measuring 45 x 50mm with most of the components
professionally soldered in. Two other components, a set of 3 brass connection terminals
and the control switch/potentiometer must be soldered in place by the user. That's the only
assembly work required.

You can connect the controller up to many 240V mains powered devices such as:
incandescent lighting, electric motors (both series wound and shaded pole) or heating
elements etc. It will control up to 3 amps (i.e. 750VA). A small heatsink may be required
on the TRIAC over 2 amps.

The kit is complete and includes all assembly/connection instructions. You only need a

suitable knob for the nylon insulated pot shaft.
ONLY $9.95

Cat. KJ-6522

VANIER AED TANIA TS UREN MEAT MAT CAT VAR VAT UAT JATUAR JATUAN JATUAR JAYTUAR JAYCAH JAYCAH JAYCAH JAYUCAH JAY UAH JAY CAH JAYULA

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MMH

MELBOURNE
Vd

DIGITAL MULTIMETERS

45 A'BECKETT STREET CITY
TELEPHONE 663 2030

IBM PC/XT COMPATIBLE CARDS

@ Build your own IBM PC/XT in stages using our quality guaranteed Jaycar XT

See our 1987 Catalogue for full specs boards! # OR, upgrade your existing system with Jaycar XT boards.
Jaycar is proud to announce availability of a vast range of support boards for

1, FREQUENCY COUNTER DMM + =
CAPACITANCE METER + TRANSISTOR == cuaaeel teil by eon lenmatanien juiegaine

TESTER + 20 AMP CURRENT + HIGH elo
IMPACT CASE = tiustrated) cat. aM-1555 1/O PLUS Il CARD

Provides one serial port, one parallel port and joystick port.

Cat. XC-5016 $ 1 39.00
MONO GRAPHICS/PRINTER CARD

Massive 720 x 348 (2 pages) graphic resolution, with Centronics parallel port.

ey nord column (characters) x 25 lines. $ 1 8 9.0 0
UNIVERSAL 640K RAM CARD

640K of RAM using both 4164 and 41256 chips. User can select memory options

= — a DIP switches select RAM starting address. $2 4 9. 00
FLOPPY DISC CONTROLLER - 4 DRIVES

Will control up to 4 x double sided double density 360K drives (IBM).

ces" ONLY $69.00
RS232 (SERIAL) CARD

Supports two asynchronous communications

Gat xo s032 ONLY $69.00
150 WATT SWITCH MODE POWER
SUPPLY

Fully compatible with IBM PC/XT. Metal case. Provides +5V@ 15A, -5V
@ 1A, +12V @ 5A and -12V @ 1A from 240V input.

re ONLY $159.00
PC/XT COMPATIBLE KEYBOARD

84 keys. Plugs into case

sae" ONLY $179.00
1OMHz TURBO MOTHERBOARD

The board will operate at either 4.77MHz (standard) or at 10MHz.

“ee ONLY $499.00
COLOUR GRAPHIC VIDEO CARD

It will give RGB, TTL, composite video colour or composite video in monochrome to a
ena $139.00
COLOUR GRAPHIC/PRINTER CARD

Provides printer AND monitor interface. Has one parallel printer port, composite colour,
RGB CTTC outputs as well as composite mono-chrome video output with display buffer.

Cat. XC-5022 S 1 59.00
MULTI 1/O BOARD

Will drive 2 x double sided double density floppy discs, one serial port, one parallel

Por and ane joystick or games or. 8 1 9 9 0 0
PC/XT COMPATIBLE CASE

Simi 0 the real one! Will house your XT cards. $ ] 1 5.00
PARALLEL PRINTER CARD

This card provides a parallel interface for Centronic printers such as the Epson RX80,
JAYCAR JA

—_ ele ONLY $59.00
JAYCAR COMPUTER CARDS WORK HARDER |

JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JA’
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$169.00

2. 10 AMP DIGITAL MULTIMETER WITH
TRANSISTOR TEST FACILITY

(Not illustrated) Cat. QM-1530 $89.95

3. 10 AMP DIGITAL MULTIMETER +
TRANSISTOR TESTER + CAPACITANCE
METER net iitustrated) Cat. QM-1540

NORMALLY $129.00 JUNE ONLY
LESS 15% - NOW $109.65

4. 4.5 DIGIT +
DIGITAL HOLD +
10 AMP

+ TRANSISTOR
TESTER + AUDIBL
CONTINUITY
TESTER

(Not Illustrated) Cat. QM-1550

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$179.00

NEW KITS FOR JUNE
AEM 6508
AUDIO CLIPPING FAULT INDICATOR

REF: AUSTRALIAN ELECTRONICS MONTHLY JUNE 1987

This unit is designed to indicate an overload condition (i.e. clipping on DC faults) in your
amplifier. It consists of a PCB and all board components. A clip indication LED is then
mounted on the front panel of your amp.

The unit can be calibrated for amps from 5 - 250 watts).

Kit supplied is for one channel only)

ca \M% ONLY $19.95 (2 required for stereo)
ETI 283 CUSTOM TELEPHONE RINGER KIT

Ref: ETI June 1987

Connect this to your home or office phone (with a double adaptor) and generate your own
space age telephone ring tone! Can be adjusted to give veru ‘spacey’ arcade game like
noises! If you work in an environment where you cannot tell if it's your phone that is ringing,
this Is for you. Case and all electronics included.

Double ad. ‘Cat. YT- $7. $
er gl t 6020 $7.50 extra) 39.95

TTC ee

3 JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR
3 JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR

ae ee ae ee ee

eum

¢ NEW PRODUCTS NEW

Pinetree Meane | RECTIFIER DIODE
: O sdk | 6 AMP 1000V

$2.20 Gale

| R-1024
Heatsink compound large tube ~NM-2010 $ 1 50 ea
$18.95 og 10 up $1.30 ea

es ee eee ee ee es

Mi

45 A'BECKETT STREET CITY
TELEPHONE 663 2030

CAR BRAKE LIGHT

For safety sake you need one of these.
Easy to install. Mount it on your rear parcel
shelf, and it allows several cars travelling
behind you to see when you hit the brakes.
Soon to become compulsory on new cars.
Cat. XM-0600

| BNC crimp male plug

CARLINGFORD
STORE NOW
OPEN UNTIL

2 pm SATURDAYS

BUTTON CELL BATTERY HOLDER

e PCB Mount
e Will take all common silver oxide cells + small lithium batteries etc.

* Gold plated contacts $3.95 10 UP $3.50 ea

HAVE YOU DESIGNED A UNIQUE PRODUCT?

Jaycar is continually on the lookout for innovative new products
involving electronics. If you are a clever engineer/designer and have
invented that great new product maybe we can help youl Jaycar has the
capital and marketing expertise to get that product off the ground.

We are quite flexible in negotiating royalties/commissions etc., but we
will have to get one thing straight right from the start. If you contact

us you MUST provide us with sufficient information for us to asses what
you have. We WILL NOT copy your idea and pay you nothing, but you
will have to trust us. We reserve the right to return your submission if
we believe that it is either not unique or does not have sufficient
technical merit. You will at least get a professional assessment of your
idea/invention for no chargel

So what have you got to lose? Maybe we can make you a millionaire!

CONTACT GARY JOHNSTON (personally)
etic TODAY (02) 747 2022
PS-0844 a

eucete || SCOOP BUY!
240V - 6V 300mA PLUG ADAPTOR

ps.os4e | |
PP-0890 |
We have made a genuine scoop purchase of approved 240 - 6V DC 300mA plug pack
power supplies. They feature an extra long lead (great for remote power points!) and the
usual 4 way cruciform connector and polarity reversing plug. Interestinly they have 2 x
2.5mm outlets as well.
At this price we suggest that you buy one or two whether you need them at present or
not, At BELOW HALF the price of our regular cheapest adaptor they're an incredible

Cat iP ONLY $7.95!

LOWER EVERYDAY PRICES
ON CENTRONICS AND “D”
CONNECTORS

These are NOT a special for one month only, these are our NEW LOWER everyday prices.

WERE TYPE 1-9 10 UP 100 UP Cat. No
INC TAX
$1.20
$1.60
$1.20
$1.40
$1.60
$1.80
$1.25
$1.70
$1.80
$1.25
$6.00
$6.25
$5.00

$2.75
$3.50
$2.20
$3.25
$3.95
$5.75
$2.20
$3.95
$5.25
$2.20
$12.50
$12.50
$12.50
$12.50
$15.95
$17.50

9 pin Male D

9 pin Female D

9 pin Backshell

15 pin Male D

15 pin Female D

15 pin Female R/angle
15 pin Backshell

25 pin Male D

25 pin Female D

25 pin Backshell

25D IDC Plug

25D IDC Socket
Centronics Plug
Centronics IDC Plug
Centronics Socket
Centronics IDC Socket

$2.25
$2.75
$1.90
$2.50
$2.75
$3.50
$2.00
$2.95

$2.00
$2.50
$1.80
$2.25
$2.50
$3.25
$1.80
$2.70
$3.20
$1.80
$8.00
$8.50
$7.00
$8.00
$9.50
$11.50

PP-0800
PS-0804
PM-0808
PP-0820
PS-0824
PS-0826
PM-0828

Cat. MP-3008

|
\
8 CHANNEL I.R. REMOTE CONTROL - REF: EA JUNE 1987 - NEW KIT!!

This project enables you to control up to 8 separate circuits or functions - DC or 240V AC.
With the optional add on kit the full receiver will perform such functions as up-down, volume,
muting etc. The transmitter kit is enclosed in an all ABS case with neat Scotchcal label. The
standard receiver kit is supplied with 4 relays. Extra 12V relays (up to 8 total can be fitted) are

available at $4.25 ea (Cat. SY-4061) Transmitter kit - Cat. KA-1684

IEC-TYPE MAINS
INPUT FILTERS

3 AMP

The filter is rated at
250V 3 amps. 1/4"
Q.C. type terminals
are on the top for
simple internal
mains connection.
Type IEC-320
recessed chassis

$45
Standard Receiver Kit (4 relays)
Cat. KA-1685 $1 27 95
Add on kit for volume,

up down etc. Cat. KA-1686 $82.95

CONCORD
NOW OPEN
SATURDAY MORNINGS

MUFFLERS

This fully approved Electricity Authority
unit is the ultimate mains suppression
device. It is fitted with a circuit breaker and
VDR's for extra suppression capacity.
Nothing but clean 240V goes through.
Recommended for computers - VDU's -
printers - disc drives - video - medical
equipment.

Max load 1000 watts 4 amps 250V. TURN YOUR STOCK INTO

TWO OUTLETS
Cat. MS-4040

$149.00
FOUR OUTLETS
Cat. MS-4042

$249.00

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nce aia. © a .

JAYCAR No.1 FOR MAINS FILTERS

TALL ssisisihihtittttthttttthtthhhh

plug on the side.
SPECS:
Input: 115-250V AC
47 - 63Hz

3A continuous
Size: 38(D) x 63(H) x
50(W)mm excluding
terminals.

Cat. MS-4004

$19.95 ea
10 up $17.95 ea

CAILELEEAL ELE LEED ALL LEAP OA ATA LAE ET AALS py

CASH! - Jaycar will purchase your
surplus stocks of components and equip-
ment. We are continually on the lookout for
sources of prime quality merchandise.

CALL GARY JOHNSTON
TODAY ON
(02) 747 2022
OR FAX
(02) 744 0767

GORE HILL
OPEN
SATURDAYS
UNTIL 4pm

Basically the same as the 3 amp version,
except it's 4 amp and it's fused. Accepts

3AG fuses. $29.95

Cat. MS-4006
8 AMP

For those big jobs. Again much the same
as the 3 amp one - but 8 amps.

Cat. MS-4005 $29.95

,, CARLINGFORD
% NOWOPEN
YA SATURDAYS
UNTIL 2pm

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ONE NENT ENE NAENEN ENT NOFNEN PNT NOENTN ENE NOPNEN ENT NSPE PNT NSENEN OPN TE NOPNEN FN TNE rd FNP bp tid ae eS ee Tee, MRO eee

JAYGAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYGAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR J
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NT . Ref: EA July 1986 PIGIERE ELECTRONIC

( The very latest in bret ‘protection. Polyswitch pro- Fr eee , aomatic eh ‘ REFRIGERATOR ;

tectors are based on conductive polymers and act like tig relay DEODORISER WV LN
q ‘ seat circulates the air inside 150ns

ee a refrigerator after each door opening. Air is drawn thru 1-9 $2.95 1-9 $3.50

ies Slee neal argent ia the inlet grille (shown). It passes through a special fitter 10 up$2.50 10 up $3.25

P 4 > that absorbs odours. The Frigi-Fresh automatically turns 100 $1.80 100 $2.20 ,

resistance is 0.4 ohms. ‘ h e closed eet!

| Cat. RN-3410 itself off approx 12 seconds after the door is c! . Cat. ZZ-8420 Cat. ZZ-8422 ome

RN3415 will protect midrange and woofers up to 100
| watts. Rated at 50V & 1.15A. Nominal resistance is
0.12 ohms.

Cat. YF-5522 (inc. fitter)
Spare filters Cat. YF-5523 $3.00 each $2 49
Requires 4 x AA cells (not supplied) .

AIR OUTLET

BOTH UNITS Cat. PA-0888
$6.98 ea C.0.S.
10 or more L.E.D. POWER

\ $6.50 each INDICATOR

BATTERY TESTER

Two probes coming out of one end of this hand held device
are Inserted into the water to be tested. An instant reading
of the Chiorine level and pH value is given on the panel
meter display. Battery — and = for fish tanks tool
Cat. QM-6135

om ee SS SS SO OS OO ee ee ee eS ES SO ee Oe ee ee eo ee eee

Ideal for alarms or anywhere where constant use depletes
batteries quickly.

iCads 12 VOLT 1.2A/H "Seas
Cat. SB-2480 $28. 50 é Pe

Don't keep wasting money buying throw-away batteries.
, 12 VOLT 4.5A/H
toN les.
ae mie = stale! cut Cat. SB-2486 isis cl

Cat. SB-2452

$3.50 ea This oe doos everything!
EATUR
4 desi . " 2 . * Charges: B AAA, AA, C or D cells at once
seat * Charges 3 to 9V cells via universal connector
¥ hoad PVA ET * Charges 3, 6 and 12V Gel batteries
Plenuren * Charges button cells
* Operates from 240V mains * Test meter and LED charging
* Accepts AA, C, D & 9V NiCads * 240V operated

* Charges singly or in groups
* Charge different size units together
* Charging indicator lamp at each
battery position

ee battery test facility

isect Repe Yr Cat. MB-3508
This one is $15.50 ‘cheaper
than last yearl
It will control mice, rats, roaches,
crickets, silversfish, waterbugs,
moths, etc.
Size: 100 x 90 x 80mm.
Power adaptor supplied 240V/
9V DC. Output level 130dB from

30kH? to 65kHz. ONLY $39.50

Cat. YS-5510

| We're heavily overstocked on our MT-2136 Toroid. It is a
| 300 VA unit with two separate 30V 5 amp winding as
| secondaries.
{ They are normally $75 but this month you can grab one
(or 2) for only $49.95 each a massive iia ote over
331/3%ll f
Cat. MT-2136

| NORMALLY $75
JUNE SPECIAL $49.95 -

The solar panel in the lid will charge up to 4 x AA NiCads
in a fairly short time. It ls ideal for yachts, campers, or
anywhere where 240V is not avalable,
Cat. MB-3502

This handy charger will
recharge your Gel
batteries. Delivers
300mA current at
12 volts DC. Supplied
with quick connect
lugs for easy
connection to the
battery.

| Cat. MP-3506

($13.95

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G1 15 Parramatta Road
Concord 2137

( if a Y - ITY 117 York St. (02) 267 1614 -

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ia , y Mon Fi 75-30 Thurs 8.30 pm- Sao Y Polen Feees y yi
EI cCrronaice | 115 Parramatta Rd (02) 745 3077 -
™Y CLECTRONICS Z MoncFt'8 908.30 (Sot 8.30 12 Y (02) 748 0767 Z
V jyeeeemmaaaaquaveqceadad; H 121 Forest Rid (02) 570 7000 - ZG Z
G — POST & PACKING : son Mon-Fri 9 - 5.30 Thurs 8.30 pm - Sat 9 - 12 " Y PO. Box 185 % :
y (5) Mastercard. $10 $24.99 $370 7 Moncrig:5:90Sa'S-4pm AyeZ Cee Z y
Po ig Z BAN Logan Rd Buranda (07) 393 077 - A Ae HET BE i
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GZ VISA ROAD FREIGHT Z YURNE - CITY Shop 2, 41-49 ABeckett St aes . LLEREE Y
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Professional organisations for

the electronics technician

TETIA and

b INST OF AUST.
aE

all rt stands for

Ever wondered what the word “TETIA’’
stands for in the Fault of the Month item
published in the Serviceman column? It’s just
one of two professional organisations for
technicians in the electronics industry.

by JIM LAWLER

The “TETIA Fault of the Month”, at
the foot of “The Serviceman” stories,
has become one of the magazine’s more
popular features.

I have been supplying the FOTM
since its inception, and it appears fairly
regularly. On the occasions when the
paragraph does not appear, I can rely
on getting phone calls from all parts of
Australia asking ‘“‘What’s happened?”
Equally, at other times, I can expect
calls asking, “What is TETIA and how
can I join?” The fact that callers want
to join an organisation they seem to
know nothing about implies that FOTM
(Fault of the Month) is pretty powerful
material.

In fact, FOTM began about three
years ago after Leo Simpson, the then
Editor of EA, asked the same question
over lunch at the TETIA/TESA Con-
vention at Launceston. Leo had _ ac-
cepted my invitation to speak at the
Convention and then had to admit that
he knew nothing of either TETIA or its
sister organisation TESA, (of which
more later).

The explanation which I gave Leo
then forms the basis for this article. In
return he invited us to promote the In-
stitute by means of the paragraph now
known as Fault of the Month.

Mr Fixit
To know the origins of The Elec-

tronic Technicians Institute of Australia
(TETIA), it is necessary to go back to

36 ELECTRONICS Australia, June 1987

the early 1950s and look at the local
radio repairman’s shop.

In most cases he was the village “Mr
Fixit”, able to attempt repairs to any-
thing remotely based on technology.
Apart from radios, he would repair
irons and jugs, fans, toasters and radia-
tors. One man I knew even did a first
class job fixing sewing machines.

As well as repairs, the local radio
shop sold ‘wireless sets” and ‘‘gramo-
phone records’, torch batteries, light
globes and other small appliances. Most
radio mechanics also rented out public
address systems to various events and
functions.

In a word, the radio repairman was
versatile and ingenious. Above all, he
was skilled in a wide variety of village
arts. Then in 1956 came television.

The works of a five valve superhet
might have been a puzzle to its owner,
but any reasonably intelligent person
could learn the principles in a few
weeks and the practise in a year or two.
Television, on the other hand, involved
totally new principles and practises that
few people had ever heard of, let alone
understood.

The brighter and more enthusiastic
radio mechanics went back to school to
learn the new technology. Although
they were able to use their new skills as
soon as TV transmissions started, their
qualifications were slow to be acknowl-
edged by both the public and employ-
ers. Many servicemen felt that some or-

ganisation was needed to promote the
Professional status of the new “techni-
cian”.

The beginning

A group of technicians in Melbourne
started the Institute in 1956 and, under
several names, it has grown to become
a nationwide organisation with some-
thing like a thousand members. The In-
stitute is governed by a Federal Council
and Constitution, with administration in
the hands of each State Division.

Full membership of TETIA requires
both educational qualifications and
practical experience. Associate member-
ship is open to those who have either
the certificate or the experience but not
both. Apprentices and those undertak-
ing approved courses of training are eli-
gible for student membership.

The original members of the Institute
were radio tradesmen, mostly holders of
an apprenticeship certificate with post-
trade qualifications in television. The
modern version of this certificate issued
by State Technical Colleges, includes
basic television, and is the minimum
qualification for admission to the Insti-
tute.

Trade or technician certificates
awarded by Telecom, the armed ser-
vices or similar authorities, are also ac-
ceptable as membership qualifications.
Graduates of commercial correspond-
ence courses may qualify if they gain a
pass at a supervised examination ar-
ranged or approved by the Institute.

As its name implies, the Institute was
founded for the benefit of electronic
technicians and it has been argued that
a radio trade certificate is hardly techni-
cian level. But radio apprentices now
graduate with television qualifications
and often with extensive digital elec-
tronics training, quite sufficient to grade
the modern technician above the one
time radio tradesman.

Gaining this certificate requires at
least three or four years practical train-
ing. This, with subsequent post-trade
experience to a total of five years, is ac-
cepted as the minimum practical re-
quirement for admission to the Insti-
tute.

Post trade courses

So a certificate and five years experi-
ence will gain for you access to TETIA
but the learning process goes on for
ever. The Institute sponsors post-trade
courses wherever they can be organised
and has often conducted its own courses
to supplement those offered by educa-
tional authorities.

Lectures and training seminars are
held regularly and the Institute publi-
shes and distributes printed material for
the use and information of its members.
Some educational material is now being
distributed on videotape and regular
newsletters keep members up to date
with activities within their Divisions.

Every two years, the Institute joins
with TESA to stage the National Elec-
tronic Services Convention. The Con-
vention is held in each state in turn and
provides an opportunity for members to
meet each other and with representa-
tives from manufacturer’s service de-
partments. Lectures and displays pre-
sented at the convention enable mem-
bers to keep up-to-date with this fast
changing industry.

Originally the Institute catered mostly
for technicians engaged in domestic
electronics, meaning television. In re-
cent years, the range of electronic ser-
vices have spread so widely that today
membership is open to an enormous
range of occupations.

For example, in Tasmania our mem-
bership extends to employees in Tele-
com, the Hydro Electric Commission,
the University, CSIRO, the Education
Department and the Australian Broad-
casting Corporation, to name just a few.
Members are engaged in such diverse
fields as industrial electronics, medical
electronics, commercial computer instal-
lation and service, and two-way radio
installation and maintenance. There is
even one member who spends most of
his time installing and repairing electric
fences.

For most members of TETIA, our
days consist of solving problems like
those described by the Serviceman.
Other members have similar problems
in other fields or industries. For all of
us, electronics is a fascinating but ever-
changing occupation. We keep up to
date only by constant study and TETIA
is there to guide and help us.

Enquiries about membership should
be addressed to the Secretary, TETIA,
in each state. Their addresses follow:

©The Secretary, TETIA NSW Division,
762 Victoria Road, Ryde 2112.

eThe Secretary, TETIA Victorian Divi-
sion, 21 Burwood Road, Hawthorn
3122.

The Secretary, TETIA SA Division,
28 Church Street, Highgate 5063.

eThe Secretary, TETIA WA Division,
PO Box 220, Willeton 6155

eThe Secretary, TETIA Tasmanian
Division, 16 Adina Street, Geilston Bay
7015.

Queensland enquiries should be ad-
dressed to NSW Division.

All about TESA

The constitution adopted by the
founders of TETIA set the aims of the
Institute as “educational” and deliber-
ately excluded industrial or commercial
activities.

Some members of TETIA were self-
employed servicemen or the managers
of service companies and the Institute
was unable to provide assistance with
their “business” problems. It was felt
that another, parallel organsiation was
warranted and in 1962 the Television
and Electronics Services Association
(TESA) was formed.

TESA is an association of service
businesses and it is the businesses them-
selves that are the members, not the
persons engaged in the business. Usu-
ally the owner or manager is the mem-
ber’s representative at Association
meetings.

The Association speaks for members
in matters before Industrial Commis-
sions, at Consumer Protection Council
hearings, and at similar official meet-
ings. TESA is a member of a buying
group for the benefit of it’s members
and, among other things, it supplies a
range of standard business stationery at
minimal cost to it’s members.

To the benefit of consumers, the As-
sociation imposes a discipline on_ its
members which guarantees _ ethical
practises and a recourse to higher au-
thority in the event of disputes.

So TETIA and TESA work closely
with each other. TETIA looks after the
technician’s education, qualifications
and professional status, while TESA at-
tends to the commercial and industrial
side of the technician’s business activi-
ties.

Enquiries about membership of
TESA should be addressed to Mr Ray
White, Secretary TESA, PO Box 154,
Carlingford, NSW 2118. @

Looking to purchase instruments

We are stockists of Hitachi, Fluke,
Goodwill, Meguro, Aaron and Kikusui: so if
you’re in the market for an oscilliscope, think
of David Reid. ,

ESCORT
MULTIMETERS

EDM 1105 $78.89
@ 3'/2 digits. @ Six functions: DCV,
ACV, DCA, ACA, OHM, Diode Testing.
@ 0.8% basic DC accuracy
EDM 1116 $104.92
@ New model complete with tran
sistor and capacitor tester
EDM 1118 $125.78
@ 31% digits with DB range
EDM 1125 $113.95
@ 31/2 digits. @ Seven tunctions
OCV, ACV, DCA, ACA, OHM, Diode
Testing, Audible Continuity
@ 0.25% basic DC accuracy
EDM 1135 $141.00
@ 31/2 digits. @ Eight functions: DCV, ACV, DCA, ACA, OHM,
Diode Testing, Audible Continuity. @ 0.1% basic DC accuracy.
EDM 1346 $250.87
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Audible Continuity Testing, Diode Testing, Data Hold. @ 0.05%
basic DC accuracy.

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Ring us first for your 20 Meg. Oscilloscope
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FEATURES

Large 6 inch rectang

graticule CRT

CH1 & CH2 ALT Triggering
(Alternate triggering function)
High Sensitivity 1mV/div

Hold-off function $730.00
TV Sync. Separation circuit = +
CH1 Signal output 20% TAX

Plus 2 probes included in this deal.

Check out our kit range!
Here’s two to have a go at —

Megohm Meter

It uses a transistor inverter to produce a regu-
lated 1000V DC supply which is applied to the: ¢
insulation under test. Insulation resistances be- a kl A
tween 2M Ohm and more than 2000 Ohm can

be measured. K 2500 (See EA July '85) $59.00

8 SECTOR ALARM SYSTEM KIT

Features:

@ Alarm has 8 separate input circuits — 8
sectors can be monitored independently.

Each input circuit is provided with an indicator
LED and a sector On/Off switch.

Individual sector isolation allows the user to
have some areas of the premises habited while
others remain protected e.g. Inside Off/Outside

On.

@ Inputs accept both normally closed and
normally open sensors.

© Two inputs provided with an entry delay
between 10-75 seconds).

Internal trip warning buzzer — alerts
owner/occupant of pending alarm operation —
great for the ‘forgetful’ amongst us. This
buzzer is pre-settable between 5 and 55
seconds prior to Alarm.

Unique circuit detects automatically when any
N/O or N/C loops are either open circuit or
dead short. e.g. someone trying to bridge reed
switches etc

Switched output can be used to send a silent
alarm through an auto-dialler circuit or similar

K 1900 (without Back up Battery) ....
S$ 5065 (12V 1.2AH Backup Battery) ....

These are just a few of the many 100’s of up-to-
date Electronic items on display at

DAVID REID ELECTRONICS LIMITED
127 York Street, Sydney, 2000
or Telephone (02) 267 1385

ELECTRONICS Australia, June 1987 37

FORUM

Conducted by Neville Williams

Technology:
has it gone over the top?

There’s long been a readiness to question new technology —
maybe ever since that far off day when someone invented the
wheel. In a letter recently to hand, a reader who has spent his
working life in electronics complains that the industry seems
currently more interested in gee-whiz technology than in real

consumer needs.

By way of background, the writer
says that his interest in radio dates back
to the days when he had to save up six-
pence from his pocket money to buy his
copy of Radio and Hobbies — the name
under which this journal was launched
as a monthly in 1939.

The letter is too long to accommodate
in full but the abbreviated version that
follows should indicate what the writer
is concerned about. He continues:

In the past, technology was developed
to meet specific needs; large valves gave
way to progressively smaller ones, &c.
Today, it seems, technology has out-
stripped our needs and is looking for an
application.

The above remark is prompted in part
by EA’s remote controlled preamp proj-
ect — a “‘you beaut’ device, using the la-
test technology, but why? Where is the
point in selecting radio from your arm-
chair and then having to walk over to it
to change stations? Or selecting cassette
input and then having to walk over to in-
sert the cassette and press Play? Maybe
there are other useful functions but why
source selection?

Take a look at today’s TV receiver re-
mote controls. The bodies are so small
that they are difficult to handle, and the
buttons so tiny and closely spaced that
they are difficult to operate one at a
time. Again, some of the buttons are
rarely used by non-technical viewers.

I have a 6-year old remote control
which is large enough to fit comfortably

38 ELECTRONICS Australia, June 1987

in the hand, with six large buttons
providing sound up/down/mute, channel
up/down and power onloff — basic, sim-
ple and useful. Contrast this with my re-
cent attempt to buy something similar for
my 80-year old mother, who was con-
fined to a chair by arthritis. I was
obliged to settle for one too small to
handle easily and with so many tiny but-
tons that, to the day she died, she could
never figure it out.

Why are controls built like this, de-
spite the fact that they present real prob-
lems to non-technical and handicapped
people, who must surely represent a sig-
nificant proportion of the buying public?
Because technology says they can be!

Along similar lines, I recently pur-
chased an AIWA AD-WX220 twin cas-
sette deck to facilitate dubbing and edit-
ing of conference tapes. It’s a great ma-
chine but who needs the ‘Random Pro-
gram Music Sensor’? And at what cost?
Maybe it’s an attempt to keep up with
CD players, but in vain because who
wants to wait while the tape shuffles
back and forth to reach the desired
track?

Another major grouch concerns TV
and stereo sound. In a cinema, pains are
taken to match the visual and sound
images in the cause of realism but, in the
home, a typical stereo TV has the loud-
speakers immediately adjacent to the
relatively small screen. At family viewing
distance, the sound image seems little
wider than a point source and the stereo

effect is lost. If the loudspeakers are de-
tached or a hifi system is used, a full
stereo sound image will result but the
visual image remains minuscule.

The problem becomes most noticeable
with simulcasts, when the sound qualifies
as a stereo program in its own right. To
match it, the picture would require a sin-
gle stationary camera with fixed lens —
hardly the sort of visual fare to attract
viewers.

As matters stand, while listening to in-
struments in acoustically specific and
fixed positions, the TV viewer is forced
to view proceedings from different an-
gles, sometimes close-up and even look-
ing face-on to the conductor. I find it an
unreal and confusing situation, such that
I prefer either to switch off the picture,
or to retain it and listen to the sound in
mono.

A report on stereo TV sound in
“Broadcast Engineering News” (Oct.
1986) quoted comment which tended to
support my own view. It reminded me of
unofficial experiments which I witnessed
back around 1960 at ABS, Adelaide,
where the disparity between picture and
sound was evident to all.

Once again, it seems that we don’t
need the facility but the technology is
there and, if we don’t have it, the
“other” channel may steal a march! At a
time when everyone is crying poor, I
wonder about the justification — and the
ethics — of having these high technology
gimmicks foisted upon us.

D.S. (North Rocks, NSW).

It so happened that, about the time I
received the above letter, I had a phone
conversation with a now-retired profes-
sional musician and concert critic.
Prompted by a chance reference to
compact discs, he sounded off in a man-
ner that would have done credit to

someone half his age!

“Ethics”, as mentioned above by
D.S., was much too tame a word to find
a place in his outburst.

To my musician friend, rejection of
the faithful black disc and the change-
over to CDs was a scandal of interna-
tional proportions, a gigantic conspir-
acy, a massive fraud, the greatest confi-
dence trick that had ever been pulled
on lovers of good music.

In modern LPs, he insisted, the
recording industry had a medium that
offered all the quality and subtlety
needed to satisfy music lovers. But
manufacturers were looking for a new
gimmick — a new product that would
force consumers to scrap their existing
equipment and start all over again —
and they’d found it in the compact disc.

Mention of technical specifications,
the lack of surface noise, freedom from
wear, etc, served only to impart re-
newed vigour to his scathing remarks. I
gained the distinct impression that aspir-
ing CD equipment salesmen could de-
lete his name from their prospect list!

It was somewhat reassuring to recall a
review of a then new CD release by
Roger Covell in the Sydney Morning
Herald “Guide” for Feb 23. You may
have noticed it:

Rigoletto (complete opera) Callas,
Gobbi, La Scala/Serafin. EMI CDS 7
47469 8 (two discs).

Said Roger Covell: “In the long run,
the greatest blessing of the compact disc
will probably be its ability to renew old
recordings in a more or less permanent
manner...

The old EMI/La Scala version of
Rigoletto (recorded in 1955) is one of
the prime documents of 20th century
Verdi performance . . .

“CD recording not only restores the
performance to that of a mint LP, it
eliminates most of the noises made by
even the quietest LPs of the period; and
it gives the impression of improving the
basic sound in one or two of its
aspects...”

Maybe, just maybe, and despite the
foregoing passionately held conviction
to the contrary, even this new fangled
compact disc technology may have
something to commend it to consumers!

The good old days:

Getting back to D.S.’s letter, one’s
immediate reaction may well be to
agree that most of the technological ad-
vances made during past years do ap-
pear to have been prompted by an iden-
tifiable demand; but that, more recent-
ly, consumer requirements often seem

to have been overtaken by the urge to
exploit new technology for its own sake.

We must, however, allow for the fact
that recent developments are, of neces-
sity, evaluated without the benefit of
hindsight and what we lightly dismiss as
today’s gimmick may well turn out to be
tomorrow’s necessity. The promoter(s)
may simply be more astute than the rest
of us in identifying latest needs!

In the matter of remote controllers, a
great many present-day consumers are
willing to pay for the privilege of not
having to put aside their beer and
bikkies to make that tedious journey
across the room — not for every single
knob adjustment, anyway!

The remote controller for the pream-
plifier described in our October and
November 1986 issues provides for all
the functions that are reasonably access-
able in such a unit, including input se-
lection. As such, it’s essentially no dif-
ferent in concept to other controllers
dedicated to individual modules and it
remains for the buyer/builder to decide
whether it matches their needs.

Even so, I’ve always felt that the re-
mote control concept can all too easily
develop into a jungle. The mind boggles
at the idea of a complete one-brand
audio/video entertainment system with
the essential functions of every unit
brought together in a single armchair
controller. Apart from the need for a
pilot’s licence, the owner would be
locked into a particular group of com-
ponents until the day came to scrap the
entire outfit.

But the prospect of multiple indepen-

dent units, each with their own separate
controller, is not very inviting either.
It’s easy enough to mislay a single VCR
or TV remote control, without having
to search for and sort through half a
dozen of the things!

Yes, D.S., some controllers are need-
lessly small and needlessly difficult to
operate and, even without the limita-
tions of arthritis and a wheelchair, I’ve
experienced at first hand the difficulty
of finding, interpreting and manipulat-
ing them in the semi-gloom of a TV
viewing room.

Maybe we should blame the engineers
who, I am sure, found no problem at all
in manipulating gadgets of their own
creation, smaller and with more buttons
than their competitors’ models and
demonstrated to management in the
bright lighting of a conference centre!

As for AIWA’s Random Program
Music Sensor, I’m not in a position to
offer an opinion about its cost compo-
nent or its potential value to particular
buyers. I probably wouldn’t have much
use for it either but if, as a facility, it
adds only modestly to the price, it
would scarcely be worth getting uptight
about.

Frankly, I hear far fewer grumbles
about supposedly gimmick features in
consumer electronic equipment than |
do about electronic ‘“gimmickry” in
modern cars. Electronic ignition is fair
enough, because it’s an isolated fitment
and obviates the tedious chore of check-
ing and replacing distributor points. But
enigmatic electronic “brains” that con-
trol most of the works, and electronic

Interchanging VHS & NTSC tapes

Att: Neville Williams,

Firstly, full marks for an
excellent monthly column. You
might like to comment on_ the

following observations:

(1). | purchased some Memorex
T120 video cassettes in the USA
as they were much cheaper than
E180 tapes in Australia. They run
for 170 minutes here, with good

results.

(2). According to information on
the package, the actual tape is
equally suitable for NTSC and
PAL/SECAM.

(3). | have exchanged recorded
cassettes with people in the USA
but without success either way.
The National brand VCRs_ look
much the same except that the
American models use a 3-speed
system.

| am aware that the PAL and
NTSC systems encode the signal
differently for transmission from
station to receiver. A VHS tape
system, however, is presented with
decoded video and audio signals
and, although | lack background
knowledge of the subjec:, | sus-
pect that the method of retrieving
the information is the same on all
VHS units, wherever sold.

The differences in tape speed
pose an immediate problem but it
seems to me that, if VHS units
were equipped with speed adjust-
ments of sufficient range (either as
standard or user modified) then
synchronising may occur. Some
guidance in the matter may be ap-
preciated by your readers.

D.K. (Belmont, Vic).

ELECTRONICS Australia, June 1987 39

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Building your own computer then we
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are 15 function keys in addition to the 67

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Connection is again by flexible printed
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Why pay $10 more for a
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Geoff has the Jones Transformers JT353
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Specs JT353

Input: 240V 50 Hz

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Two 15V windings at 0.25A

Interlocked Push-Button
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Highest quality 5 way DPDT interlocked
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The GOS-522 is an ideal general purpose
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saves a lot of knob twiddling!! Trigger circuit is
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Trigger level lock and variable hold-off all add
to ease of use. Auto, normal and single shot

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FORUM = continued

instrument arrays that cost the earth to
replace are seen by many — rightly or
wrongly — as examples of gee-whiz
technology gone mad!

Stereo TV sound

I was interested to read D.S.’s ideas
about TV stereo sound and, in the short
term, I would have no great inclination
to quarrel with them. It is indeed true
that, when listening to good stereo
sound, one tends to visualise the layout
of the orchestra or ensemble and, ac-
cording to the mood of the moment, ei-
ther to listen to the sound as a whole or
else focus upon some particular compo-
nent of it. ,

In a live situation, the eyes would fol-
low the ears, or vice versa, with the
senses tending to complement each
other unconsciously and automatically.

In a TV stereo presentation, that fa-
cility is not available for reasons which
D.S. explains. You have either to look
at a picture which is chronically small or
else, at the whim of the video producer,

leave your ears on the seat and go flit-"

ting hither and yon with your eyes.

D.S. chooses to break the nexus by
discarding either the picture or the
stereo facility, which would seem to be
a rather drastic course. Maybe, given a
little more patience, he may learn to
concentrate rather more heavily on the
audio and to relegate the visual to a
supplementary role.

In the longer term, I would expect
the ubiquitous cathode ray tube to give
way to other forms of presentation,
which will offer a much larger and
brighter image. When that happens,
stereo sound will much more naturally
fit the picture!

A problem with standards

Still on the general subject of televi-
sion, a Victorian reader, D.K., has
been wrestling with the compatability
problem between video cassettes re-
corded on superficially similar WHS
decks but to American and Australian
television standards. His letter (consid-
erably abbreviated) appears in the ac-
companying panel.

Perhaps I should add that, although
referring specifically to National/
Panasonic VHS format VCRs, the re-
marks apply equally to other brands and
to both VHS and Beta.

While D.K. realises that the video
signal is encoded in different ways for
CCIR/PAL and NTSC transmissions, he
has not caught up with the fact that the

signal encoding on video tape is no less
distinct and different for the respective
systems.

Without getting involved in a lot of
detail, the tape in virtually all VCRs is
pulled obliquely around a polished, rap-
idly spinning drum carrying a number of
video heads. These impose the video
signal obliquely across the tape as a
series of side-by-side tracks, each track
containing the synchronising, luminance
and chrominance information pertaining
to one single field.

In the NTSC system, the field repeti-
tion rate is 60 per second, with each
field containing 525 lines. In CCIR/-
PAL, the respective figures are 50 and
625. Whichever one is recorded on the
tape will obviously be recovered on
playback and no amount of fiddling
with drum speed can translate one to
the other; it can only falsify both fig-
ures.

The linear speed of the tape affects
the width and the ‘slant of the oblique
tracks but not the field rate or the num-
ber of lines per field so, again, fiddling
the linear speed could do nothing to
bridge the gap between the standards; it
would only add to the confusion and,
for extra measure, change the sound
from drawl to “duck talk”, as with any
other linear sound recording.

One could suggest other discrepancies
to do with colour encoding, &c, but
enough has been said to indicate that
D.K.’s proposition is quite impractical.
Behind the facia of other-country
models that look superficially similar,
the differences extend far beyond the
linear speed of the tape.

If one really must view cassettes
based on other standards, or record
them for use overseas, it is possible to
buy multi-standard VCRs — but at a
price and at a likely premium for ser-
vice charges, because of the extra inclu-
sions. Moreover, you don’t normally
use them with your everyday TV set but
with a receiver or monitor which can it-
self accommodate different standards.

Sick of soldering?

Another Victorian reader has
prompted a further instalment in the
seemingly never ending saga about the
possible undesirable effects of soldering
fumes. His letter was addressed in the
first instance to Norman Marks, a for-
mer member of the EA staff, whose ob-
servations on the subject were quoted
on page 16 of the February issue. He
says:

Dear Sir,

After three months under the care of
the medical profession (no hopers) I
read in EA for February Norman
Marks’ letter to Neville Williams, which
appears to be the answer to my problem.

I am silver soldering (Easy Flow, 2
SBA rods) a copper boiler for a 5-inch
gauge model steam engine — but now, |
realise, not in the correct environment.

Could you please advise where I could
find out further information, and what is
Merck’s Index? Just head me in the right
direction.

M.W. (Essendon, Vic).

Talking the letter over with Norman
Marks, we agreed that there was no
guarantee whatever that M.W.’s indis-
position, whatever it was, had anything
to do with his model building efforts.
Even if there was a possible connection,
one wonders how a member of the
medical profession could, out of the
blue, come up with the question:

“Hmm you haven’t by any
chance been silver-soldering a copper
boiler lately, have you?”

That aside, Norman Marks empha-
sised again that it was very wise to en-
sure adequate ventilation, forced if nec-
essary, when brazing, soldering or weld-
ing. He added:

“One of the problems with hard sol-
dering, where low working temperatures
are required, lies in the inclusion of the
low melt metals such as cadmium and
cerium. If the alloy is overheated,
oxides are given off, with cadmium high
on the list of problem materials.

“Metal oxide fume ingestion can
cause what is known as ‘metal fume
fever”.

“Companies in this general field
which might be able to supply further
information include:

e Harringtons Metallurgists Ltd, 37-49
O’Connor St, Chippendale, 2008.

@ Johnson Matthey Ltd, 160 Rocky Pt,
Rd, Kogarah, 2217.

© Engelhard Industries Pty Ltd, SO Park
St, Sydney, 2000.

As for Merck’s Index, I gather that it
is a very large reference manual pub-
lished by a Division of Merck, Sharpe
and Dohme, a large American drug and
chemical company. Comprising more
than 2000 pages, it is an exhaustive
reference on drugs, industrial chemicals,
organic chemcials, natural elements,
standard tests for the presence of ele-
ments, &c.

Norman Marks managed to get a fire-
damaged copy but otherwise, he said,
“it would probably cost an arm and a
leg”. Check for it in the reference sec-
tion of any large, accessible library. @

ELECTRONICS Australia, June 1987 41

F-Il] cutaway

1 Hinged nose cone
2 Attack radar
3 Terrain-following radar
4 Nose hinges (2)
5 Radar mounting
6 Nose lock
7 Angle-of-sideslip probe
8 Homing antenna (high)
9 Forward warning antenna
10 Homing antenna (low and mid)
11 ALR-41 antenna
12 Flight control computers
13 Feel and trim assembly
14 Forward avionics bay
15 Angle-of-attack probe
16 UHF Comm/Tacan No 2
17 Module forward bulkhead and
stabilization flaps (2)
18 Twin nosewheels
19 Shock strut
20 Underfloor impact attenuation
bag stowage (4)
21 Nosewheel well
22 LOX converter
23 Rudder pedals
24 Control column
25 LOX heat exchanger
26 Auxiliary flotation bag pressure
bottle
27 Weapons sight
28 Forward parachute bridle line
29 De-fog nozzle
30 Windscreen
31 Starboard console
32 Emergency oxygen bottle
33 Crew seats
34 Bulkhead console
35 Wing sweep control handle
36 Recovery chute catapult
37 Provision/survival pack
38 Attenuation bags pressure bottle
39 Recovery chute
40 Aft parachute bridle line
41 UH :
42 Stabilization-brake chute
43 Self-righting bag
44 UHF

45 ECM antennae (port and
starboard)

46 Forward fuselage fuel bay
(2,340 Imp gal/10,638 litres)

47 Ground refuelling receptacle

48 Weapons bay

49 Module pitch flaps (port and
starboard)

50 Aft flotation bag stowage

51 Air refuelling receptacle

52 Primary heat-exchanger
(air-to-water)

53 Ram air inlet

54 Rate gyros

55 Rotating glove

56 Inlet variable spike

It’s called an F111C.

It’s a high-performance, supersonic swing-wing strike

reconnaissance aircraft.

An aircraft that has distinguished itself in several

57 Port intake
58 Air brake/undercarriage door
59 Auxiliary inlet blow-in doors
60 Rotating glove pivot point
61 Inlet vortex generators
62 Wing sweep pivot
63 Wing centre-box assembly
64 Wing sweep actuator
65 Wing sweep feedback
66 Control runs
67 pepe glove drive set
68 Inboard pivot pylons (2)
69 Auxiliary drop tanks
(500 Imp gal/2,273 litres)
70 Outboard fixed pylon
fe een wecrante)
71 Slat drive set
72 Wing fuel tank
(324 Imp gal/1,473 litres)
73 Leading-edge slat
74 Starboard navigation light
75 Flap drive set
76 Outboard spoiler actuator
77 Starboard spoilers
78 Inboard spoiler actuator
79 Flaps
80 Wing swept position
81 Auxiliary flap
82 Auxiliary flap actuator
83 Nuclear weapons and weapons
control equipment package
84 Wing sweep/Hi Lift control box
85 Flap, slat and glove drive
mechanism .
86 Starboard engine bay
87 Yaw feel spring
88 Roll feel spring
89 Yaw trim actuator
90 Yaw damper servo
91 Roll stick position transducer
92 Pitch trim actuator (manual)
93 Roll damper servo
94 Pitch trim actuator (series)
95 Pitch feel spring
96 Fitch-roll mixer
97 Pitch damper servo
98 Pitch stick position transducer
99 Aft fuselage frames
100 Aft fuselage fuel bays
(1,191 Imp gal/5,413 litres)
101 Horizontal stabilizer servo
actuator
102 Starboard horizontal stabilizer
103 Aft warning antennae
104 HF antenna
105 Detector scanner
106 X-Band radar
107 Rudder
108 Integral vent tank
109 Fin aft spar
110 Fin structure

“Now putit backto

You're looking at a technological marvel.

combat zones around the world.

It’s a very complex machine made up of more than
three million separate parts, each and every one vital to

the aircraft's performance.

Indeed, for every hour of flying time, it must spend
many on the ground being checked, double-checked and

checked once again.

By perfectionists.

The men and women who perform the many tasks
needed to keep it flying are RAAF technicians.

They learn their skills through our Certificate of
Technology, Trade Apprentice and Adult Technical
Training Schemes.

Quite frankly, RAAF technicians represent the very
best in their various fields.

These include avionics, armaments, electronics,
propulsion systems and even fibre optics.

Once posted to operational duties, we expect them to
very quickly put themselves on a first-name basis with

103

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gether, Corporal?

every nut, bolt, rivet and electrical circuit of their aircraft.

And that could be any one of the 17 different types
currently in service with the RAAF.

If this sounds demanding, you’re absolutely right.

But these are the characteristics that make RAAF
technicians the most sought-after by civilian employers.

If you think you've got what it takes to be the best in
your field, fill in the coupon and send it off now.

All we require is that you're an Australian citizen.*

You must be between 16 and 21 with good results in
English, Maths and Physics (17-34 years for Adult
Training). You should also be reasonably fit.

*Or eligible to become one.

Name

Address

Telephone

Highest Educ. level attained or being studied —_PPPJ_>»>_E
Or phone an RAAF Careers Adviser on Adelaide 212 1455. Albury 218277. Bendigo
43 8008. Brisbane 226 2626. Canberra 57 2311 Geelong 211588. Hobart 347077.
Launceston 311005. Melbourne 697 9755. Newcastle 26 3011. Parramatta 635 1511.
Perth 325 6222. Sydney 2195555. Townsville 72 4566. Wollongong 281855.

GROUNDCREW @ RAAF

Authorised by Director-General of Recruiting, Dept. of Defence.

103

1 Fin/fuselage attachment

2 Rudder servo actuator

3 Variable nozzle

4 Tailfeathers

5 ECM antenna

6 ALR-41 antenna

7 Horizontal staviiizer structure

8 Horizontal stabilizer servo
actuator

9 Free floating blow-in doors

0 Afterburner section

21 Horizontal stabilizer servo

actuator

122 Wing swept position

123 UHF

124 Ventral fin

125 Fire detection sensing element

loops

126 Cross frames

127 Engine access hatches

128 Engine accessories

129 Pratt & Whitney TF30 turbofan

130 Three-stage fan

131 Intake duct

132 Fire extinguishing agent

container and nozzles

133 Wing box skinning

134 Port mainwheel

135 Auxiliary drop tanks

136 Pivot pylon

137 Pivot point

138 Pivot actuator

139 Flap racks

140 Fixed pylon strong point

141 Outboard fixed jettisonable

Bylen

142 Wing integral fuel
143 Wing box structure
144 Port navigation light

11
11
11
11
11
11
11
11
11
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j

Postcode

Date of Birth

Eight-channel IR

remote control

Ever wanted to fit remote control for your TV
set, CD player, VCR, cassette player or even
your model railway? Or do you have
appliances or machinery which would be
safer or more convenient if operated by
remote control? Up to eight separate
functions can be switched with this infrared
remote control and you can add power on/off,
muting and volume control.

by JOHN CLARKE

The remote control system to be de-
scribed could be added to a pushbutton
TV set which presently does not have
the luxury of remote control. Alterna-
tively, if mains-rated relay switching is
added, it could be used to control appli-
ances such as lamps, alarms, heaters
and so on.

Model railway enthusiasts can build
the circuit in a number of versions and
use it to control points and signalling on
a track layout.

Basically, the remote control unit can
operate any device which is normally
controlled with momentary or change-
over contacts. This includes solenoid-

The project can be used to provide full remote control for a TV receiver. This version of
the transmitter uses the smaller of the two optional plastic cases.

44 ‘ ELECTRONICS Australia, June 1987

operated cassette players, CD players,
pushbutton TV sets, some machinery
and models.

The remote control comprises a small
hand-held battery-powered _ infrared
transmitter and an accompanying re-
ceiver unit. The receiver is mains pow-
ered and can be built with a minimum
of components to provide remote con-
trol of up to eight functions with
momentary or latched relay contacts.
The addition of the full complement of
components allows control of on/off,
muting and up and down volume.

The transmitter can include up to 12
switches to enable the use of all remote
control features, or only include those
switches that are necessary for the num-
ber of functions on the receiver. For in-
stance, only eight switches need be used
if the receiver is built to control eight
outputs only.

Operation of the remote control relies
upon a coded signal which consists of
pulses of infrared light. The receiver
uses an infrared diode to detect the
transmitted IR light. The resulting
pulsed waveform is applied to a decoder
IC which provides an output to select
the function determined by the trans-
mitter. Outputs are relay contacts which
have the advantage of complete isola-
tion of each output plus the choice of
normally open or normally closed con-
tacts.

A choice of decoders provides for ei-
ther latched (ie, stays on after being se-
lected) or momentary contact relay out-
puts. The latched output decoder can be
one of two types. One type simply is a
4-bit output suitable for selecting each
of the eight relays. The second type has
the 4-bit output plus a separate output
for mute and volume control.

If momentary contacts, volume and
muting are all required then two decod-
ers are required.

The volume control output is a cur-
rent source which can be used to di-
rectly control volume on DC volume
controlled TV sets or via a Light De-
pendent Resistor. The LDR connects
across the volume control potentiometer

2xCQYB9A,LD271

1c1
SL490B

VIEWED FROM
BELOW

Ea) REMOTE CONTROL TRANSMITTER

The transmitter circuit. IC1 delivers a series of pulses to drive the two infrared LEDs.

and provides complete isolation from
the receiver circuit.

Circuitry

The transmitter circuit comprises one
SL490B integrated circuit (IC1), two
transistors, two infrared (IR) LEDs and
a few resistors and capacitors. The IR
LEDs transmit a pulse position modula-
tion (PPM) 5-bit code whenever one of
the switches is pressed.

We have used 12 of the possible 32
separate code commands available with
the SL490B. Connections for the
switches are arranged in a matrix form
from pins 6 to 15 and ground. The code
for each matrix line is shown on the cir-
cuit. This means that switches 1 to 8
have codes from 01000 to 01111, while
the Up, Mute and Down switches have
codes 10100, 11001 and 11100. The OFF
switch sends the code 00100.

The transmitter circuit is actually very

4BAx20mm SCREWS

4BAx4mm CSK SCREWS

Fig.la: this diagram shows how the two transmitter PCBs are in-
stalled in the larger case. The IR LEDs protrude through holes

drilled in one of the end panels.

similar to and compatible with the re-
mote control for the Playmaster Stereo
AM/FM Tuner (described in the July
1986 issue of EA). The 8-channel keys
and the on/off key would therefore op-
erate the tuner memory, up/down tun-
ing and AM/FM selection. The Mute
and the Up and Down volume controls
will not affect the tuner.

The transmit code output is at pin 2
of IC1, which is AC-coupled via the
0.068 uF capacitor to the base of transis-
tor QJ. This produces a 15uS current
pulse each time pin 2 goes low. The
1000, resistor at the base of Q1 ensures
that Q1 is off after each 15s pulse. Q2
is driven by Q1 via a 33Q resistor which
in turn drives the IR LEDs with the
short high current pulses.

The PPM rate of transmission is set
by the 33k. resistor and 0.224F capaci-
tor. Filtering for the internal 4.5V sup-
ply of the SL490B is provided by the

he

it cae I, =o

Rr LED

ter.

Fig.1b: PCB mounting details for the optional smaller case.
this version, the IR LEDs are positioned behind a red plastic fil-

ELECTRONICS Australia, June 1987

4.7u4F capacitor connected between pin
17 and the OV line.

Power for the transmitter is derived
from a 9V battery while a 220uF ca-
pacitor across the supply provides the
high current surges required when the
IR LEDs are pulsed on. The standby

current of the circuit is less than 104A.

Receiver circuitry

IR diode DS is the detector for the
transmitted IR signal. It is connected
across the differential input stage of 1C2
at pins 1 and 16. The differential input
stage provides for rejection of common
mode noise from the diode and connect-
ing leads.

Following this is a gyrator and four
gain stages (all inside IC2). Each of
these has a low frequency roll-off below
2kHz to effectively reject any 100Hz
signals picked up by the receiver diode.
The 6.8uF, 47pF, 0.015uF, 0.0334F
and 0.0047uF capacitors at pins 2, 3,
15, 5 and 6 respectively are used to pro-
vide this roll-off.

A 0.15uF capacitor at pin 8 filters the
output from an internal peak detector
which measures the final output at pin
9. The resulting signal is used to auto-
matically control the gain of the first
three amplifier stages.

The input to an internal regulator at
pin 12 is supplied via a 2200 resistor to
reduce the supply voltage and is filtered
with the 22«F capacitor. Supply decou-
pling between the sensitive input cir-
cuitry and the output circuit is via the
47Q, resistor and 0.33F capacitor.

After amplification in IC2, the re-
ceived signal is sent to the input of IC3
and/or IC5. These devices convert the
received serial stream into a 4-bit paral-
lel code. (This means that they can only
decode 16 of the possible 32 codes from
the transmitter).

Both decoders contain an internal os-
cillator and this is at pin 2 for ICS and
pin 1 for 1C3. The 0.0274F capacitor
and series connected 22k) resistor and
50k trimpot provide the reference fre-
quency for each of the decoder ICs. In

4BAx20mm SCREW
AND NUT

15mm SELF TAPPER
RED FILTER

pel

(R LEO

=~ 5mm SELF-TAPPER

INTEGRAL SPACERS

In

45

Above & below: actual size PC artworks
for the transmitter.

ing the eight channel selections plus
Off. Mute, Dn and Up. For those func-
tions not required, the switch associated
with that function can be deleted.

Construction of the transmitter can
begin with the assembly of the PCBs.
The pushbutton switches must be in-
stalled with the flat side of the switch
oriented as shown on the accompanying
diagram. We used green for the cight
channel switches, white for the Mute,
Dn and Up switches, and black for Off.

The transmitter circuit board should
be assembled using the wiring diagram
as a guide. Start by soldering in the IC
and resistors. Before installing the re-
mainder of the components, it is easier

46 ELECTRONICS Australia, June 1987

Here’s a sneak preview of the IR remote control receiver to be described next month.

to solder in the wires for connection to
the other PCB.

We used a 50mm-long piece of 10-
way rainbow cable to do this job. The
wiring is at ICI pin numbers 6, 7, 8, 10,
11, 12, 13, 14, 1S and ground. Note that
if the Off, Mute, Dn and Up switches
are not used, then wires into pins 6, 10,
1] and [2 are not necessary.

All the capacitors lie side-on to allow
the switch PCB to stack on top of this
board. The 220aF capacitor is mounted
off the edge of the PCB using the leads
to support it in this position.

Transistor QI is inserted hard down
onto the PCB, while Q2 is bent over as
shown in the photograph. The infrared
LEDs are mounted above the PCB by
about 5mm, and their leads bent so that
they protrude over the edge of the PCB
by about 7mm.

The 9V battery clip can now be sol-
dered in place. Wiring from the 87tr5
PCB is made to the underside of the
87cp5 PCB to the pads designated for
each pin number of ICI. This allows
both PCBs to be stacked together as
shown in Fig. 1.

Fig.1(a) shows how the PCBs are in-
stalled in the larger case while Fig.1(b)
shows the mounting details for the
smaller case. Fig. l(a) shows the 87tr5
PCB supported on 12mm _ tapped
spacers from the base of the case while
the 87ep5 PCB is supported above this
using untapped 9mm_ spacers. The
LEDs protrude through holes drilled in
the front face of the case.

Fig.1(b) shows the 87trS PCB sup-
ported on the integral spacers in the
base of the case. The 87cp5 PCB is sup-
ported above this using untapped 9mm
spacers. The LEDs are positioned so
that they are located just behind a red
plastic filter. The filter measures 59 x 25
x 0.8mm and is slotted into the front of
the case.

Install the PCB assembly in the box
and measure the distance from the first
row of switches to the front of the box.
Use this distance and the front panel
artwork to mark out the hole locations
in the front panel. Remember to mark
out only for the number of switches
used.

Drill the holes out carefully with a
4mm drill and ream each hole out to
Ymm diameter. Check that the lid will
fit without fouling any of the switches.

Two front panel labels have been de-
signed. One will suit if the unit is used
as a remote control for a TV set while
the other would suit as a control for a
CD player. The appropriate label can
be affixed to the front panel and the
switch holes cut out with a sharp knife
and reamer.

If used, the smaller case requires a 59
x 25 x (0.8mm red filter in the front
opening. This can be either perspex or a
circularly polarised plastic filter.

Finally. connect up a 9V battery and
screw down the lid. That completes con-
struction of the transmitter.

Next month we will describe the con-

struction of two versions of the receiver. ®

PARTS LIST FOR IR REMOTE CONTROL

TRANSMITTER

Transmitter

1 PCB, code 87cp5, 44 x 62mm

1 PCB, code 87tr5, 40 x 57mm

1 front panel, 65 x 120mm

1 9V battery clip

1 plastic case, 65 x 120 x 40mm

(W x H x D) or 67 x 110 x 33mm

(see text)

1 red filter, 59 x 25 x 0.8mm (for
smaller case)

4 9mm untapped spacers

4 12mm tapped spacers

8 green PCB pushbutton
switches

3 white PCB pushbutton
switches

1 black PCB pushbutton
switches

The receiver circuitry is installed in a
standard plastic instrument case.

RECEIVER
(8-RELAY CONTROL
ONLY)

PCB, code 87rc5, 173 x
146mm
PCB, code 87pa5, 46 x 46mm
transformer PL12/5VA
mains cord and plug
cord clamp grommet
grommet for mains cord
cable clamp (for transformer)
plastic instrument case, 200 x
160 x 70mm (W.-x H x D)
piece of tinplate 70 x 70mm
(optional)
piece of tinplate 47 x 47mm
(optional)
8 DPDT 12V relays (Jaycar or
Altronics S-4061, or Original
OUB12V from Hi-Com Unitronics)

Semiconductors

1 SL490 remote control
transmitter

2 CQY89A or LD271 IR LEDs

1 BC327 PNP transistor

1 BD139 NPN transistor

Capacitors

1 220uF 16VW PC electrolytic

1 4.7uF 16VW PC electrolytic

1 0.22uF metallised polyester

1 0.068F metallised polyester

Resistors (0.25W, 5%)

1 x 338kQ, 1 x 2.2kQ, 1 x 1000

0.25W, 1 x 330, 1 x 1.80

Miscellaneous

Screws, nuts, solder, 50mm of
10-way rainbow cable

Semiconductors

1 SL486 remote control
preamplifier

1 BPW50 or BP104 IR diode
1 ML926 or ML928 remote
control receiver

1 4051 8-channel analog
demultiplexer

1 4011 quad two-input NAND

gate

1 7812 12V three terminal
regulator

8 BC337 NPN transistors
12 1N4002 1A diodes

Capacitors

1 470uF 25VW PC electrolytic
2 47uF 16VW PC electrolytic

1 22uF 16VW PC electrolytic

1 10uF 16VW PC electrolytic

1 6.8uF 16VW PC electrolytic

1 2.2uF 16VW PC electrolytic

1 0.33uF metallised polyester
1 0.15uF metallised polyester
1 0.033uF metallised polyester
2 0.027uF metallised polyester
1 0.015uF metallised polyester
1 0.0047uF metallised polyester

Resistors (0.25W, 5%)

6 x 56KQO, 1 x 22k0, 1 x 4.7kQ, 1
x 2200, 1 x 470, 1 x 50k
horizontal 10-turn trimpot

Miscellaneous

Screws, nuts, PC stakes, hookup
wire, solder etc.

ELECTRONICS Australia, June 1987

RECEIVER (FULL VERSION)
PCB, code 87rc5, 173 x 146mm

PCB, code 87pa5, 46 x 46mm

transformer, PL12/5VA

mains cord and plug

cord clamp grommet

grommet for mains cord

cable clamp (for transformer)

plastic instrument case, 200 x
160 x 70mm (W x H x D)
1 piece of brass shim or tinplate,
70 x 70mm
1 piece of brass shim or tinplate,
47 x 47mm
1 DPDT 12V 5A relay
9 DPDT 12V relays (Jaycar or
Altronics S-4061, or Original
OUB12V from Hi-Com Unitronics)
3 38mm red LEDs
1 Light Dependent Resistor
(Philips 2322 600 95001 or
Jaycar Cat. RD-3480, or similar)
Semiconductors

1 SL486 remote control
preamplifier

1 BPW50 or BP104 IR diode

1 SL486 remote control preamplifier
ML923 remote control receiver
ML926 remote control receiver
4051 8-channel analog
demultiplexer

4011 quad two-input NAND gate
555 timer

7812 12V 3-terminal regulator
BC558 PNP transistor

BC547 NPN transistor

BC327 PNP transistor

11 BC337 NPN transistors

1 TIP32 PNP transistor

14 1N4002 1A diodes

3 1N914, 1N4148 diodes
Capacitors

1 470uF 25VW PC electrolytic

3 47uF 16VW PC electrolytic

1 22uF 16VW PC electrolytic

1 10uF 16VW PC electrolytic

1 6.8uF 16VW PC electrolytic

2 2.2uF 16VW PC electrolytic

1 0.33uF metallised polyester

1 0.15uF metallised polyester

1 0.1yF metallised polyester
10.
2

a ot

—

033uF metallised polyester
0.027uF metallised polyester
1 0.015uF metallised polyester
1 0.0047uF metallised polyester
Resistors (0.25W, 5%)
1 x 3.38MQ, 2 x 100k, 7 x 56k,
2 x 39kQ, 2 x 33kN, 2 x 22k0, 1
x 10k, 1 x 6.8k, 4 x 4.7kQ, 1
xX 2.2kQ, 2 x 4700, 1 x 2200, 1 x
47Q, 2 x 50kQ horizontal 10-turn
trimpots
Miscellaneous
Screws, nuts, PC stakes, hookup
wire, solder etc.

47

IC6 selects one of the eight outputs
according to the code at the A, B and C
inputs. This switches on the associated
transistor to power the accompanying
relay. The diode across each relay
quenches the back EMF of the coil and
prevents damage to IC6 and the associ-
ated transistors.

Note that each relay is a double pole
double throw type to duplicate the ac-
tion of double pole switches used in
some equipment. For selection of the
relays to take place, the INH input to
IC6 must be low. Consequently, when
IC3 or the ML926 (ICS) is used for se-
lection, the D output is inverted so that
the D-bar signal can be applied to the
INH input of IC6.

When the ML928 is used for ICS, in-
version of the D output is unnecessary
since the outputs are already inverted.
This also means that the order of relay
selection will not comply with the relay
numbering designated for the ML926
and ML923 ICs. Instead of being se-
lected sequentially from 1 to 8, the
order is 6, 5, 7, 8, 2, 1, 3 and 4.

Apart from providing latched A, B,
C and D outputs, [C3 has an analog
output at pin 10 and Mute control at
pin 8. The Mute output goes high for
muting and is low otherwise. For each
transmitted Mute signal, the output at
pin 8 changes state.

The analog output at pin 10 is a cur-
rent mirror which delivers up to 1.3mA
in 32 increments. The down transmis-
sion reduces the current while the up
transmission increases the current. It
takes about three seconds to span the
entire current range with the transmitter
Up or Down button continuously
pressed.

When power is first applied, the RC
time constant at pin 17 resets the analog
output to 3/8th the maximum current
and the muting is reset. The 0.1uF ca-
pacitor and 3.3MQ. resistor at pin 7 al-
lows correct operation of the muting
and analog steps.

The current output from pin 10 of
IC3 is fed to a series resistor string con-
sisting of a 6.8kQ and 39kQ resistor,
the latter being shunted by transistor
Q4. The voltage across Q4 can be used
for controlling DC volume controls of
TV sets. As an alternative, a Light De-
pendent Resistor (LDR) provides for a
fully isolated volume control that can be
substituted for a conventional potenti-
ometer.

This facility is provided by Darling-
ton-connected transistors Q5 and Q6
which are driven from the collector of
Q4, via a 39kQ) resistor. Q6 drives two
LEDs through 470Q resistors from the

48 ELECTRONICS Australia, June 1987

Alternative version of the transmitter, mounted in the larger of the two standard cases.
Leave out the buttons for those functions that you don’t need.

12V power supply. The LEDs in turn
provide light for the LDR so that its
resistance changes with the varying cur-
rent available from pin 10 of IC3.

Muting here, muting there

Muting of the current source at pin 10
of IC3 occurs under three separate
conditions whenever diode D6, D7 or
D8 is forward biased. When this hap-
pens, Q4 turns on and shorts the volt-
age at its collector to ground. This also
causes transistors Q5 and Q6 to turn on
fully and drive the LEDs to full bright-
ness. This gives minimum resistance
through the LDR.

Diode D7 is forward biased when the
Mute output at pin 8 of IC3 goes high.
This happens under two conditions. It

could be in response to a Mute signal
from the transmitter or if the transmit-
ter volume down switch brings the out-
put on pin 10 of [C3 to a minimum.

Diode D8 is forward biased for mut-
ing whenever the output of IC4 at pin 3
is high. IC4 is a 555 connected as a mo-
nostable timer with a timing length of
about 240ms. Triggering of the timer
occurs whenever the AFC output of IC3
at pin S goes low. This occurs for every
code transmission from the transmitter
which changes one of the eight output
relays.

When pin 5 of 1C3 goes low it trig-
gers IC4 and sets its output at pin 3
high. For as long as the transmitter
switch is pressed the AFC output will
supply low going pulses to the base of

LED2

Here are the parts layout diagrams for the two transmitter PCBs. The numbers adjacent
to various pads correspond to the external wiring points (see also photo page 46).

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battery for the frequent
user, resulting from
exhaustive research,
sophisticated product
development and
high-tech production.
Recharges up to 1000
times. This is the '
economical alternative i509 Rs
for constant long lasting
trouble free operation.

Positively the
Battery Experts

RSH 4

VIC: 150 Buckhurst St. Sth Melbourne 3205. (03) 690-4911. Telex: Adeal AA 37011.

NSW: 405 Sussex St. Sydney 2000. (02) 211-0422

Distributed bv ADEAL ti 1D, Te

(07) 299-6992. S.A. (08) 258-5865.
(09) 279-8811.

Allen-Bradley MOD POT-Now you can
have the best when you want ae

The most versatile standard pote
today - mix and match thea
for over 1 billion A, 3

Because the Allen-Bradley Mod Pot, which has a world-
wide reputation for consistent quality and performance,
is assembled right here in Australia at our newly-
established Mod Pot assembly centre. The entire
standard Mod Pot range is now

available for extra fast delivery

to anywhere in Australia -

Allen-Bradley, the company

you can rely on.

FEATURES:

@ Hot moulded Carbon.

@ Cermet.

@ Conductive Plastic.

@ Single or Concentric
shafts.

@ Push/Pull or Rotary
switches.

@ PC Pin Type or Lug
terminals optional.

@ Vernier Drives, 4 or
16 turns.

i) ALLEN-BRADLEY
wy

A ROCKWELL INTERNATIONAL COMPANY
Design excellence and quality in the best tradition.

, pre-tested
” or 4 control
ne OS of variable
tOrs to solve your unique control
Lae

Call your Allen-Bradley
Electronic Components
Sales Centre today, and
you'll be amazed at how
fast we will deliver.

er

Allen-Bradley, 75 years of cost effective, innovative

electronic component manufacturing.
ei 37 Chapman Street, Blackburn 3130. Ph. 899-0335

N.S.W.: 22 Parramatta Road, Lidcombe 2141. Ph. 648-2652

QLD.: 1925 Logan Road, Upper Mt. Gravatt 4122. Ph. 343-7900
W.A.: P.O. Box 23, Subiaco 6008. Ph. 387-1702
S.A.: Electronic Components and Equipment

30-40 Hurtle Sq., Adelaide 5000. Ph. 232-0001
A.C.T.: Electronic Component P/L. P.O. Box 534,

Fyshwick 2609. Ph. (062) 80-4654

Q3. This transistor discharges the 2.24F
capacitor to keep the timer output high.
When the transmission ceases, the 555
timer output goes low after 240ms and
unmutes the circuit.

Finally, diode D6 is forward biased to
cause muting whenever transistor Q9 is
off. Q9 is switched on whenever the
output of IC7b goes high. This occurs in
response to an off signal from the trans-
mitter. Relay 9, the power relay, then
turns off and removes mains power to
the remotely controlled appliance via its
normally open contacts.

Consequently, diode D6 is forward
biased via the denergised relay 9 coil to
provide muting when the power is
switched off.

Muting on power off is done so that if
a direct DC connection is made be-
tween the TV volume control and the
DC output of IC3, there is no voltage
present when power to the TV is
switched off.

Note also that transistor Q7 is
switched on and off via [C7a which has
a low output when the power relay is

TV
REMOTE CONTROL

off. The IC7a output follows the IC7b
output. Thus, Q7 is switched off when
the power to the remotely controlled
appliance is switched off. Q7 controls
the power to the LEDs so that LEDs
are not driven during power off and this
conserves power consumption. As soon
as power is re-applied, the output of
IC7a goes high to supply power to the
LED driving circuit.

When muting occurs, the drive from
D6, D7 or D8, apart from driving Q4,
also turns on Q8. This transistor powers
the Mute relay RLA10. This relay can
be used to switch off the loudspeaker of
a TV set, or to switch the volume con-
trol potentiometer to provide complete
volume cut-off.

LED 5 is connected across the Relay
10 windings to indicate both when the
volume is muted and also when the re-
motely controlled appliance is powered
off.

Power for the receiver circuit is de-
rived from a PCB mounted mains trans-
former which provides 12VAC. This
feeds a bridge rectifier, D1 to D4, and a

PLAY

PAUSE

OFF

470F filter capacitor. The unregulated
DC is fed to a 7812 3-terminal regulator
to provided a fixed +12V DC output.

Transmitter construction

The remote control transmitter is con-
structed on two printed circuit boards.
One PCB accommodates the pushbut-
ton switches and measures 44 x 62mm
(code 87cp5); the other accommodates
the remainder of the circuitry and mea-
sures 40 x 57mm (code 87tr5).

The transmitter can be housed in one
of two cases. The first is a standard
plastic case measuring 65 x 120 x 40mm
(W x H x D) and available from many

kitset suppliers. The alternative is
smaller but more expensive, has a 9V
battery compartment, and includes

provision for a plastic window in the
front of the unit. It measures 67 x 110 x
33mm and is available from Hi-Com
Unitronics, 7 President Lane, Caring-
bah, NSW 2229.

The 87cp5 PCB can accommodate up
to 12 switches, all of which are required
for the full remote control circuit featur-

BACK NEXT
° °
REV FF

STOP REPEAT
°

CD

REMOTE CONTROL

These actual-size front panel artworks can be used with the larger case.

ELECTRONICS Australia, June 1987 51

theory, both of these oscillator inputs
could be tied together and only one set
of oscillator components used. In prac-
tice though, we found that this resulted
in [C3 not operating.

One of two ICs can be used for IC5,
either the ML926 or the ML928. The
former provides momentary 4-bit out-
puts while the latter provides latched
4-bit outputs.

For the ML926 IC, the outputs nor-
mally are low until a correct code is re-
ceived from the transmitter. It responds
to the 1 to 8 selections with the D out-
put going high. Reception of selection 1
results in the D output going high and
the A, B and C outputs low. For selec-
tion 6, A, B, C and D are all high.
These outputs are maintained until
cessation of the transmitted signal,
whereupon the outputs return to zero.

For the ML928 IC, the outputs are
initially high until a correct code is re-
ceived from the transmitter. It also re-
sponds to the 1 to 8 selections with the
D output going low. Reception of selec-
tion 1 results in a low D output and
high A, B and C outputs. For selection
6, the A, B, C and D outputs are all
low. These outputs remain latched in

secured by a metal clip.

the state of the last received signal until
a new transmission changes the output
code. The A, B, C and D outputs for
IC3 are latched and have the same logic
sense as the ML926. That is, the out-
puts are normally low at power-on and
the D output goes high when a correct
code is received.

Note that either IC3 or ICS can be

This view shows the transmitter PCBs installed inside the larger case. The 9V battery is

connected to the eight channel demulti-
plexer (IC6). This is to allow the omis-
sion of IC3 when volume control and
mute is not required. When muting and
volume are required together with
momentary contacts for the 1-8 outputs,
IC3 is used for volume and mute only,
while the A, B, C and D-bar outputs of
ICS connect to IC6.

The transmitter is built on two PCBs which are wired together using ribbon cable. The BD139 transistor and the 220uF and 0.22uF ca-
pacitors must be mounted as shown so that the PCBs can be stacked together.

52 ELECTRONICS Australia, June 1987

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ELECTRONICS Australia, June 1987

Bonus Free Carry Case
(Q 1019 $4.50 Value)
This Month

Includes Continuity Buzzer
20,000 Ohms/Volt DC @ 8,000 Ohms/Volts AC. Mirror back-
ed scale © Overload protected. 10 amp DC current range.
Unique carry handle doubles as a bench stand.
RANGES
DOC Voltage
2.5, 10, 50, 250, 1000V
AC voreae
10, 50, 250, 1000V
Decibels
—8db to +62db
DC Current
5, 50, 500mA
Ohm meter 0-6 meg.
Ohms in 3 ranges,50
Ohms centre scale.
Size 135 x 91 x 39 mm

Includes Battery Tester

FOR NEXT DAY JETSERVICE DELIVERY

Why a Toriod?

Please Note: This product is a genuine
Pan Brake Bender allowing you to make
quite complex chassis, boxes, lids, trays
etc. — It is made from solid steel and is
not to be confused with inferior Non Pan
Brake simple benders currently sold by
our competitors.

Value Plus
T 2400 .... $99.95

The finest 9V Nicad on the market.
Genuine 9V (many others are actually

7.2V)
Why Pay Over $20

S 5024
Great Sashns

Over Conventional E.I.
Transformers

$17.50

And when you wani a little Technical
help or advice, just call, our staff are all
Electronics Enthusiasts — Just like
yourself.

Make Your own
Chassis and Cases
and Save a Fortune

Ca

AUSTRALIAN

MADE

Dimensions and Weight
160 VA Models 110 Diam. 45mm
H. 1.8Kgs Leads 200mm
300 VA Models 125 Diam. 45mm
H. 25Kgs Leads 200mm

FOR NEXT DAY JETSERVICE DELIVERY

¢ Smaller size and weight to meet modern “slimline”
requirements ® Low electrically induced noise demanded by
compact equipment ® High efficiency enabling conservative
rating whilst maintaining size advantages. ¢ Lower operating
temperature @ Simple, quick single bolt mounting.

SEC.V
1242
18 + 18
25 + 25
30 + 30
35 + 35
40 + 40
45 + 45

Cat.No.
M 3050
M 3055
M 3060
M 3065
M 3070
M 3075
M 3080

SEC.V
12 +12
18 + 18
25 + 25
30 + 30
35 + 35
40 + 40
45 + 45

Cat.No.
M 3085
M 3086
M 3088
M 3090
M 3092
M 3100

M 3105

MICRON T2440

S 5400 200mm x 175mm $1
Normally $1.95 each

Alarm Stickers

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MICRON T2440
ELECTRONIC TEMPERATURE CONTROLLED TEMPERATURE
EE.SOLDERING STATIO!

The MICRON T 2440 soldering station, offers
the ultimate in controlled temperature hand
soldering. 320°C, 350°C, 380°C, 410°C (608°F,
662°F, 716°F, 770°F and 824°F) fixed
temperatures are selectable by rotating the
detained rotary switch freely without changing
heater or tip.

Heat Capacity Full 48 Watts

© Temperature Control +or - 3 deg.C @
Zero Voltage Switching ¢ Grounded Tip e
Low Voltage Element 24V e Chrome

Plated Tip. T 2440
44985

Normally
This Month

SPECIFICATIONS:

Power Output
Effective Range

20 Watts max

Approx. 400M (up to
1KM in ideal conditions)
8 Pcs Cell (not Included)
230 Diam. 360 Length
1.5K (less batteries)
Supplied

Power
Dimensions
Weight
Shoulder Strap

BANKCARD HOLDERS— PHONE ALTRONICS TOLL FREE 008 999 007

@ FOR DESPATCH P&P CHARGES AND ADDRESS DETAILS PLEASE REFER TO OUR AD. ON PAGE

FOR NEXT DAY JETSERVICE D

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Why Pay
$49.95

NOW $30

Pestrepeller is effective in controlling mice,
rats, roaches, fleas, flies crickets, silverfish,

waterbugs, moths ants and most other
common pests. Laboratory research has
shown ultrasonic sound waves attack the
auditory and nervous systems of most
common pests causing them pain and
discomfort. Specifications— Dimensions:
100 x 90 x 80 Power Supply adaptor
supplied 240/9V Frequency Range 30KHz
to 65KHz variable Output Level 130db.

Super nifty little pickup
coil with suction pad, lead
and 3.5mm plug. Great for

recording or amplifying
phone conversations.

A 0485....$2.95

Cat. D1141

$189

If you have trouble with fine PCB work or
component identification but still want
both hands free, this is for you. We
thoroughly recommend this quality
Australian made product.

TECHNICAL INFORMATION Illumination:
22W Fluorescent Welght: 8.16kg Lateral
Extension: 254mm Vertical Extension:
254mm Fixing: Heavy table base (grey &
Ivory) with two chrome plated flexible
arms. Cat A 0980

A 0980

1-99 90¢
100 Up 60¢ each

Be Quick

With memory Re-Dial Great for use as a 2nd
phone around the House or Office. This nifty

little phone has all the features of
units selling near twice the price!
Last number Re-Dial memory

and Mute Key. Rings

On/Off switch and

Dialing indicator

A 0490
sex $20

casi

EMMI MNN

Fitted with 6.5mm Stereo plug light
weight and comfortable. Amazing
performance for low cost phones.

Pi
C 9001 ge

A 9315

wae C
; q 9 ean
$4957 $5 \ pr vos’ es

TIN PLATED
Pack of 1000 Buy Bulk and Save

H 0806
H 0810

Suits all Beta Video Players. Why risk
expensive damage with inferior units.

A 9300 -$4e50° $8.00

Great For storing all IC's. Protects CMOS
LSI's etc. from static damage. Stores up to
150 IC's on one sheet.

H0O600 Only $3.95 Save $1

A VH8/BETA Video Tape Repair Kit. No need to throw out your damaged
tapes—this nifty splicing kit can save you a fortune (if you've got small

children this ki

it will save you several fortunes!!) All accessories included

for joining tape and retixing leader ends etc. Cat.No. A 9315

sg TTT

Superb light weight High Fidelity
Stereo phones. Super comfortable to
use. Somarium Cobalt Magnets.
Frequency response to 20KHz.
Weight 42g.

Simply Brilliant Mylar Stereo headset
and Dynamic Mic combination.

Phones 30-18KHz 28 Ohms, 6.5mm
Stereo Jack Max. input 400mm Mic.
84db, 600 Ohms, 6.5mm Mono Jack.

C 9050......... $29.50

CANNON TYPE
CONNECTORS

Rugged reliable connector for every-
day. use.
WERE
P 0960.3 Pin Line Male $5.50
P 0962 3 Pin Chas.Male $4.25
P 0964.3 Pin Line F. $5.50
P 0966 3 Pin Chas.F. $5.98

This natty little amplifier includes some
remarkable features which, until now have
only been available on very expensive
commercial items e.g. Balanced Mic Input-
This enables you to run very long
microphone leads without troublesome
interference or hum pickup. Balanced line
output - This enables you to run the speak-
er lines right alongside the microphone line
without instability. Constant voltage
design allows you to switch on one speaker
circuit or all circuits together without any
noticeable variance in output sound level.

0.9mm $25.90

4.2mm $25.90 The RS-232 Surge Protector is used

QUALITY IMPORTED
RS-232 ACCESSORIES

D 1510 $19.50

to protect RS-232 ports from the
possibility of costly damage from
large voltage peaks caused by
lightning or other power problems.
The surge protector used Metal-
Oxide Varistors (MOV) to protect
pins 2,3 and 7. The MOV’s will
suppress any voltage above 26 volts
without affecting the normal RS-232
voltage levels.

D 1520 $9.95
The RS-232 Jumper Box is used to
make custom RS-232 interfaces. It
consists of a small board with a
connector on each end.

D 1500 $19.50

This Tester indicates the presence of
all important interface lines by LED
illumination when signal is active.

D 1530 $9.95
The RS-232 Null Modem is used to
replace a set 25-pin RS-232
connectors with transit DATA and
receive DATA CROSS CONNECTED
(Pin 2 of each connector goes to pin3
of the other connector). Pins 1 and7
are connected straight through.
Each connector is set up in the loop
back mode with pins 4 and 5 shorted
together and pins 6,8 and 20 shorted
together. The RS-232 Null Modem is
used when the proper operation of a
set of modems is in doubt. It also is
handy when Transmit DATA and
Receive DATA need to be reversed.

F 1020 80mm Diam. $24.50
4 or More $21 -00

E 008 999 007 e

FOR NEXT DAY JETSERVICE DELIVERY

HOLDERS— PHONE ALTRONICS TOLL FREE 008 999 007

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e PHONE YOUR ORDER — ALTRONICS TOLL FREE 008999007 e

Strobe Signal Lamp
Uses Xenon Strobe tube for High
energy strobe flash output ata rate
approx. 1 per second.Fantastic
light energy output for the DC
power used. DC input 12V
320mA Dimensions 97 dia.90H

Protect Your Home for Just Soe
New Ultra Sonic Home/Office
Alarm System

Fantastic system for this price. Frankly we were amazed at the
performance of this very compact system.

Very simple to connect and operate — New Technology has enabled very
compact overall dimensions (master unit only 180 x 100 x 65) hence ideal
for concealing among book shelves etc

S 5455 Blue $2459

With Pan & Tilt Adjustment
This brilliant monitor stand

enables you to swivel left/right and

tilt up/down i.e. to position
monitor to any desired position.
Hence viewing position is
enhanced and screen glare
eliminated. Cat.D 1100

Why Pay $50

Look At The Features:
Exit Delay
Entry Delay
DC Source
Battery Backup

30 - 35 secs.
10 secs
9V Nicad Rechargeable
(additional Cost S 5024 $17.50)
Auto Reset 3 minute operate cycle and auto reset.
Range Reliable to 30ft. (9M)
Low Battery Indicator Included.
Accessories Included for the one Low Price
4 Sets Reed Switches for Window/Doors
1 Roll fig "8" cable
1 External Type Horn Speaker
1 AC/DC plug pack adaptor
Now there is no excuse for not Protecting yourself,
your family and all your hard earned possessions!

S$ 5310 Only Pol

Out performs our main competitors system which,
Incidently sells at around $50 more for the
comparable system and accessories.

World Glass
Build Yourself Kits

IL

See Electronics Australia Sept ‘86 full kit K 5090
If your budget won't run to the $600 to $800 needed for a fully imported pair
of equivalent speakers, these are the ones to go for.

Some extracts from Electronics Australla Magazine — Each woofer has a foam roll
surround and a doped paper cone with an effective (piston) diameter of about 155mm
The Tweeters ‘the Tweeters are exotic little beasties” (Editor EA Magazine) eachisa
19mm soft dome unit witha ferro-fluid damped voice coil for high power handling anda
very smooth frequency response. Its resonant frequency 1s around 1 7kHz

Power Handling (60 watts plus RMS!) In an average sized lounge room and driven by
the Playmaster Sixty-Sixty or an equivalently rated amplifier, these speakers will
deliver enough sound volume to satisfy the most power crazed enthusiast
Construction Only the most basic of tools are required to assemble these loudspeakers
Even if you are a rank amateur at carpentry you will have no problems putting them
together You don't need special clamps or jiggs and all timberwork has been precisely
machined You do have to be able to use a soldering iron though, to connect the
loudspeakers to the crossover network

MAINS TRANSFORMER

7/9 VA Rating. Super Compact,
wound on Grain Oriented Steel
Core tor High efficiency and low
temperature rise.

POWER RATING:

7VA Load Full voltage +3% -0%
9VA Load Full voltage +6% to -8%

Model Prim/SEC’s
M7012 240/6+6
M 7015 240/7.5 + 7.5
M 7018 240/9+9
M 7024 240/12+12
M 7030 240/15+15

Overall Height 35mm
Length 43mm
Width 36mm

$12.50
$11.00
$10.00

PINOUT
VIEWED FROM UNDERNEATH

‘40 Sy

op |e

1EC Tt

23.5

{--

1—9
10—24
25 Plus

Altronics have just purchased around 1 Million (yes million) factory fresh,
premium quality IN914/IN4148 diodes. These became surplustoFairchild
Australia as the factory supplied bulk, loose pack diodes instead of the /
tape/reel diodes ordered. So unless you are a manufacturer with
automatic component insertion equipment, these fine quality diodes
represent the diode bargain of all time!! Cat. Z 0101

1-99 3¢ ea

100-499 2.5¢ ea VY #3

500 plus 1.5¢ea “<“
I

(HNUUQUUDUQUUOUQUEOAQUQOLGVEOOQUOUGUVOOASUOUGUUOUASUOLSUOOCGUOOUGHUOUAUEOGAUOUGAUOUULAI
Don't Be Mislead

The Altronic 60-60 Kit is the genuine product as per the construction article. It employs
the genuine Toroid Power Transformer — the resultant low noise obviates any
necessity for additional D.C. supply electrolytics as one of the other kit suppliers feels
are necessary with his kits!! There is absolutely no need to pay more than the Altronics
price for the fantastic 60-60 amp.

(EA May,June,July ‘'86)
Features:
© 60 watts per channel into 8 ohm loads © Very low noise on all inputs - better than CD
performance ® Very low distortion @ Excellent headroom ® Tape monitor loop ® Tone
controls with centre detent and defeat switch © Mono/stereo switch @ Toroidal power
transformer ¢ Easy-to-build construction @ Very little wiring.

Performance Specification
Power Output — 8 ohms 62W Distortion - Less than .0% at 1kdz. Frequency Response -
Phono Inputs - RIAA/IEC equalisation within + - 0.5db from 40Hz to 20kHz
Line Level Inputs — -0.5db at 20Hz and -1db at 20kHz Input Sensitivity - Phono 1kHz
-4.3mV ® Line Level - 270mV. Hum & Noise - Phono - 89db e High Level Inputs - 103db.
Tone Control - Bass - + -12db at 50Hz Treble - +-12db at 10kHz. Damping factor - At
1kHz and 30Hz - greater than 80 Stability — Unconditional.

CESS

“This New Amplifier offers a standard of performance far ahead of any-
thing we have previously published and ahead of most commercial
Integrated Stereo Amplifiers”.

“It Is half to one third of the cost of an imported Amplifier with equivalent

power output and performance”. Says Leo Simpson Managing Editor
Electronics Australia Magazine.

Beginner constructors can Bulld this Amplifier Kit — It looks terrific and
will last you a lifetime.

Save $200 or more on comparable performance commercial units

¢ PHONE YOUR ORDER—ALTRONICS TOLL FREE 008 999 007 °

FOR NEXT DAY JETSERVICE DELIVERY

PHONE ALTRONICS TOLL FREE 008 999 007

BANKCARD HOLDERS—

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FOR NEXT DAY JETSERVICE DELIVERY...

BANKCARD HOLDERS — PHONE ALTRONICS TQ

e PHONE YOUR ORD

Stunning Design Makes Your
Tape Machine Sound Like
A CD Player

(See ET! Dec.'86)

Dead easy to build and (even better) there
are only 3 electrical connections required
to the car wiring system.

K 4010......... $39.50

Yin,

Pigg

emis

y Wf pai Mlle, A
Sigg

Precision time your Processing
with this low cost Project

This classy digital timer allows prescision
timing for photographic processing from 1
second up to 9 minutes 59 seconds in 1
second increments.

Features: Large easy to read LED displays.
Hold switch which interrupts timing and
focus switch which bypasses the timer
settings.

Great Value

Checks audio & RF circults

(See EA Aug.’85)

This simple signal
tracer makes a
valuable servicing aid
and can be used to
trouble-shoot both RF
and audio circuits. It
features an RF probe,
battery operation and
an in-built loudspeaker

——

Cut that annoying type hiss and

dramatically increase dynamic range of
your cassette recordings with this Dynamic
Noise Reduction System It.

This fantastic system improves signal to
noise of your tape deck by up to an
incredible 18dB without treble attenuation.
It also expands dynamic range, allowing
greatly improved recordings from compact
disc players.

K 5575......... $99.00

VIDEO ENHANCER

Sharpens up your picture when
copying Video to Video

Here's a simple but effective video
enhancer that is super easy to build at a
fraction of the cost of commercial models.
Unit sharpens picture detail, and can
actually improve the quality of a copy by
amplyfying the top end of the video signal.

K 5825......... $35.00

Electronics Australia Project. Tests Bipolar
Transistors, Diodes, Fets, SCR’s and PUT's
Excellent service aid for the hobbyist and
serviceman. Complete Kit and instructions.

K 2525......... $25.00
Ultrasonic Pest Repeller

Build EA's new "Pest-Off" and save a small
fortune on insect sprays.

The “Pest-Off" generates frequencies
between 23KHz and 64KHz. Claimed to be
the best for driving off most vermin

K 1600

s

K 4400
$29.50

This Ultrasonic Movement Detector
provides added protection against illegal
entry via. an open window etc. Connects
directly to an alarm with a normally open
input. Detects any movement up to 3
metres within an angle of 30 degrees. Will
operate directly off 12V i.e. Car Battery etc.

(ETI Dec.'82)

High Performance balanced line
input pre-amp — makes a superb Mics
\/P Stage -30idb gain. :

ALTRONICS KIT FEATURES:

¢ 5534 AN's for super low noise

e TL 071 Bifet Op Amp (Great
common mode rejection ratio)
genuine Texas instruments.

SPECIFICATIONS:

e Frequency response (10K load)
—12Hz —60KHz + 0.1db

e T.H.D. (output)—100Hz 0.007%

—1KHz 0.006'% —10KHz 0.012%

© Input impedance—nominal
560 Ohms

© Output impedance—nominal
260 Ohms

© Common.mode rejection ratio—
easily adjustable to 80db,

Based upon a Single LM 382 IC

This Unit contains all necessary
components to complete:-

¢ A Phono Pre-amp with RIAA
frequency response

© A tape Pre-amp with NAB response

¢ A microphone Pre-amp with either

40,55 or 80d of gain.

© Or a Pre-amp for just about
anything!

Pre-amp may be powered by any DC
Voltage between 10 and 40 volts. The
output being automatically biased to
about +6 Volts. High 100db Ripple
Rejection

K 5510.

Reduces snow in low signal areas.

K 1798 ......... $39.00 K 5800...

Here is a high power, general
purpose power Amplifier module
suitable for HiFi, guitar and PA
applications employing sturdy,
reliable MOSFET's in the output
stage.

SPECIFICATIONS:
Power Output

150W RMS into 4 Ohms
100W RMS into 8 Ohms
(At onset of clipping)
Frequency Response
20Hz to 20KHz +0 -0.5db
10Hz to 60KHz +0 -3db
(Measured at 1 W and 100W Levels)
input Sensitivity

1 Volt RMS for full output

Hum

98db below full output

Noise

114db below full output

Total Harmonic Distortion
0.006% @ 1KHz 12W

0.038% @ 10KHz 12W

Stability

Exceptional (tested to full output
driving 3.3uF into short circuit at

Ms

K 5112
$19.50

All components mount entirely on
one printed circuit board, even the
heatsink!

SPECIFICATIONS:
Input Impedance 100K Ohm approx.
Load Impedance 4 Ohms or Greater

PWR PWR
INTO INTO
4 OHMS 8 OHMS
6.6W
12W
19W

DC IN
20V
30V
35V

=]

Ideal for Parties, Shop Signs, Display
Windows, special lighting effects etc.

Combination Colour Organ and Light
Chaser. Four channel colour organ
operation. Output lamp load capacity

a massive 2400 watts.
$115.00

e PHONE YOUR ORDER—ALTRONICS TOLL FREE US ved 007

ER — ALTRONICS TOLL FREE 008999007 ¢

|

BANKCARD HOLDERS— PHONE ALTRONICS WOLL FREE 008 999 007

-RVICE DELIVERY

FOR NEXT Di.

, : j é This simple FM
"Simply plugs Into Your Multimeter’ i E % ' Microphone iit oily -
By simply plugging this handy little ¥ ‘ ' requires an ordinary
tester into your multimeter, it allows K 6005 $24.50 Radio for reception
you to read out the actual Zener Zi 2 e runs from single 9V battery

voltage of any Zener Diode up to 60 ‘ ® High Sensitivity * Long
volts and wil also test LEDS! a8 wel as See EN eaten: USE range approximately 100 f

give you a reading of its forward Suitable for - Drills and Drill Presses - Circular Saws - Ji ® Wireless Microphone @ Professional Eavesdropping
voltage drop. K 2620 Saws - food Mixers - Movie Projectors. a © Listen to the TV in the kitchen © Makes an excellent

$12.50 child minder. K 4106 $9.50

FANTASTIC HI TECH - HI SPEC

Unbelievable 0.005% Accuracy

* frequency and Period measurement to
500 MHz (with optional prescaler) * High
Input sensitivity. Professional unit at a
fraction of the cost of bullt up units.

This Ultra low distortion oscillator is comparable with the very best laboratory standard
sine wave oscillators. As well as having very low distortion it has excellent envelope
stability, square wave output and output metering

2 Models to choose from (metered and unmetered)
© Frequency range 10Hz - 100KHz in 4 ranges @ Output level 3V RMS max adjustable =
® Attenuator Odb, -10db, -20db, -30db, -40db, -50db plus fine adjustment ¢ Output #€5) ONGITAL FREQUENCY METER 7
impedance — 600 ohms unbalanced ® Output waveforms — sine and square. } Pe) 7 1d 4 719 yl @

° Extend fluro Tube life by 1000's of
hours ® Mounts on single PCB ~ fits All components mount on one single PCB.making it a breeze to Construct

rapid start no more fheker © Nongnt Sa¥@ $200 and More by Building this Fine KitProject ® @
ase een eer K 2540 Complete Kit with Front Panel Metering $155 ee ee
* IC sockets provided throughout * Low

K 2545 Complete Kit Without Metering $139 B06 Tale 20,000 MEX AG « Quallty, ABS

plastic case with deluxe front panel *
Specified LS1

FOR NEXT DAY JETSERVICE DELIVERY

FOR NEXT DAY JETSERVICE DELIVERY

poe $149.50

Great for Voice Control of PA Systems. g . ‘ a See ee * K 2501 $42.00
Transmitters, Tape Recorder, Slide : i oe : 3 us é
Projector, Intercom etc.

K 5540......... $14.95 ee ” = — K 2502 $12.50

‘

wy
§

3-30V to 1 amp Max.with
variable current limit

FREE 008 999 007

Controlled by the latest Siemens Light
Dimmer IC. The S 576A.

Instantly turn lamps on and off with just a

igh h 1. Alternativel A :
Lae see alin ar longtion 162 laman teeny or 1200 Baud one way, 75 Baud the other. A switch has been incorporated allowing you

desired level by merely touching the panel Select either 1200 baud.
for two or three seconds - very classy!

Supplied With Gold Touch Plate K 9600 A Fantastic Performing Modem Only $169
K 6319 .......... $35.00 '

paaiilitiililille

FEATURES: $ 79.00

* Output 3 to 30V at 1A * Short circuit
protected * Load switching * Current limit-
ing. Dual scale meter * Housed in our
Deluxe "ABS" instrument case
SPECIFICATIONS:
: r * Output Voltage - 3 to 30V * Output
~~ “ aN, Current - 0 to 1 amp (fully variable) * Load
DIMMER Regulation - Better than 0.2% from 0 to full
Operate your touch load * Output Ripple-Less than 2mV RMS.
ii; lamp dimmer from : : Cat. K 3210
' your favourite arm ANNES os NHL
chair!

kK 6322 $25.00 we hdlbelll (EA Sept.’86)
; The Ideal Power Supply For The Audiophile Experimenting
With Linear O Amp Designs Controls the temperature of your standard
p g soldering iron. Suitable for irons rated from
e Floating Ground @ Meter Switchable V to A @ Voltage adjustable to within 10mV 20W—75W - Standard soldering iron plugs
e Output + or - 1.3V to + or - 22V at 2 Amps + 5V @ 1.0 Amps. K 3320 straight in, no need for modification.

MICROWAVE OVEN The Altronics Kit comes complete — pre-
LEAKAGE OE RECTOR &® punched and silk screened.

oT ee FURL SGALE - \ \ \ — : K 6400

NO BATTERIES REQUIRED

Monitor your microwave oven with this
easy to build kit. All components mount on
single PCB, including the meter.

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BANKCARD HOLDERS— PHONE ALTRONIC

(See EA Mag.Jan '85)
Fantastic Value

Be oman ee
[288eseeey] |, FEATURES:

Alarm has 8 separate input circuits - 8 sectors can be monitored
independenty. Each input circuit is provided with an indicator
LED and a sector On/Off switch. Individual sector isolation.
Inputs accept both normally closed and normally open sensors.
Two Inputs provided with an entry delay (between 10-75 sec.)
Internal trip warning buzzer - alerts owner/ocupant of pending
alarm operation - great for the “forgetful amoungst us. This
buzzer is pre-settable between 5 and 55 seconds prior to Alarm.
Unique circuit detects automatically when any N/O or N/C loops
are either open circuit or dead short. e.g. someone trying to
bridge reed switches etc. Switched output can be used to senda

Save $$$
on the cost
of commercial

silent alarm through an auto-dialler circuit or similar. Full battery
equivalents back up via. 12V - 1.2Ah battery. Supplied in an attractive
Within the functional security case.
Capacity of
the beginner
constructor
K 1900 (without Backup Battery) $139.50

$5065 12V 1.2AH Backup Battery $22.05

We process your order the day
received and despatch via. Overnight
Jetservice Courler for delivery next
day Country areas please allow
additional 24-48 hours. Weight limit
3Kaqs.

FOR NEXT DAY JETSERVICE DELIVERY

174 ROE STREET,PERTH
FOR INSTANT SERVICE

PHONE ORDER

e PHONE YOUR ORDER — ALTRONICS TOLL FREE 008999007

Low-Cost Unit Checks

Values from 1pF to 100uF

240V Mains Power
From Your 12V Battery

liitiitihonny
UY

SSR

Uy
Wh.

K 6752 Com

SES

iota eeeh229..00

Altronics Resellers

Digital Capacitance
Meter Checks capacitor
value from 1pF to 99.99uf
over three ranges.
Features include a nulling
circult and bright 4-digit
LED display.

(See EA Aug. '85)

300 Watt Inverter with
Auto Start
(See EA Sept.'85)

Just think how handy is would be to have
240 Volt AC Mains Power when camping or

for your boat or Caraven.

Auto Start draws power from your battery

only when appliance is plugged in and
“turned on" i.e. battery can be left
permanently connected if desired.
Thermal Over Load. Current Regulated.
Current Overload.

K 6754 Fully built & tested $329

Chances are there is an Altronics Reseller right near you - check
this list or phone us for details of the nearest dealer.

Blue Ribbon Dealers are highlighted with a ™.These Dealers,
generally carry a comprehensive range of Altronic products and
kits or will order any required item for you.

Scientronics......

Frank Beech
548334 Electronics...... 301379

Electronics...... 337327

Techniparts .... 3710879

~~ 00° } For Don't forget our Express Mail and Phone Order Service - for the
fo) TOLL FREE pig id excoellig oe ed less cost of a local call, Bankcard, Visa or Mastercard holders can
o 008 999 007 go GUOw.f cays [or de very phone order for same day despatch.
po PERTH METRO orders of 10Kgs. or more must travel Please Note: Resellers have to pay the cost of freight and
AND A/HRS Express Road - Please allow 7 days insurance and therefore the prices charged by individual Dealers
(o>) for delivery. may vary slightly from this Catalogue - in many cases, however,
© (09) 328 1599 — As with virtually Dealer prices will still represent a significant cost saving from
oO every other Australian supplier, we prices charged by Altronics Competitors.
[o) send goods at consignees risk.
: , Should you require comprehensive
uw Western Australia 6000 insurance cover against loss or
3 PACKING & DELIVERY CHARGE damage please ae to order value
(minimum charge $1).When phone
Le ag DELIVERY srg tig FIDE ordering please request "Insurance". If you have a Retail Shop, you could increase your income
- We process your order the day Pe Bere hoor :
m= received and despatch via. Australia | Bankcard Holders can phone order significantly by becoming an Altronics Dealer. Phone Steve
ME Post. Allow approx.7 days from day toll free up to 6pm Eastern Standard Wroblewski (09) 328 2199 for Details.
you post order to when you receive Time. Remember with our Overnight
‘ ar 9
sf goods. Weight limited 1Kgs. Jetservice we deliver next day.
ORANGE
mo LWA VICTORIA INSW aa COUNTRY
re) COUNTRY CITY CITY CITY Electronics...... 626491 CAIRNS
— ALBANY Electronic Active David Reid RAYMOND TERRACE Thompson Instrument
V4 pp Comp & Equip. 2125999 Electronics m.. 6023499 Electronics .. 2671385 geo ; 873419 Services... 512404
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ESPERANCE Electronic #... 2122672 Components .. 6623506 BLACKTOWN aman Electro Mart...... 914270
cc Esperance Protronics ... 2123111 Ellistronicsm.... 6023499 Wavefront r sp sth 362204 BUNDABERG
- Communications 713344 SUBURBAN MaGraths Electronics.... 8311908 TOUKLEY —— Bob Elkins
- BRIGHTON Electronics... 6631122 GARINGHAH Electrontcses:cs: is 721785
GERALDTON i TES Electronics .. 964144
BF 5 Electronics Brighton 3531 SUBURBAN Hicom WINDSOR GLADSTONE
Ww & Marine........ 212176 Electronics @ .. 296 ASPENDALE Unitronics.... 5247878 48 E Electronics # Supertronics ..... 724321
KALGOORLIE CHRISTIES BEACH = Giltronics ...... 5809839 LEWISHAM Communications .775935 MACKAY
S Todays electronics #.. 3829966 CHELTENHAM cio 5699770 WOLLONGONG Philtronics@ ...... 578855
: * Talking lectronics.... Newtek
aa ae ee Electronics... 5502386 SMITHFIELD Electronics@.....271620 NAMBOUR
oa aa seni =.. 3496340 CROYDEN Chantronics .... 6097218 — Madjenk , Electronics ...... 411604
Secon 854836 PROSPECT Truscott COUNTRY Electronics ...... 743061 PALM BEAGH
| aaDuah — Jensen Electronics #.. 7233860 ALBURY Vimcom — The Electronic
seat Electronics ».. 2694744 PRESTON Webb's Electronics... 284400 Contre .vuaneven 341248
7) —— bie 351246 COUNT Preston Electronics @ ....254066 QUEENSLAND ROCKHAMPTON
jetravision...... ; Electron
MT.GAMBIER Electronics.... 4840191 COFFS HARBOUR
OO Beran 751734 South East SPRINGVALE Coffs Habour CITY World .........05 278988
LU BBC) Bape ronics...... 250034 acti Electronics ...... 525684 Delsound P/L .. 2296155 Access Electronics
WYALKATCHEM Electro Active _—
o Fas Pease 811132 PT.LINCOLN Electronics #.. 5471046 poerene SUBURBAN A ssid elses pints
RTOS oe West C: t omorrows f
oO Elect Capeiles ... 825802 Se Electronics @....247246 en (Shopping Fair) .280100
s 411411 ; Electro-Mart..... 914270
x KCJohnson @ .... Kurri Electronics .372141 Electronics...... 278952
DARWIN = earioets 454764 MORWELL NEWCASTLE FORTITUDE VALLEY TOOWOOMBA
[@} Ventronics ....... 813491 TASMANIA Morwell D.G.E.Systems ...691625 ae ; seeara0 Hants
‘eq ALICE SPRINGS Electronics ...... 346133 George Brown & SCUOMGe ice Electronics @....329677
Pq Ascom HOBART 342033 SALE Company ....... 696399 ge bala 523762 TOWNSVILLE
O Electronics...... 521713 George eTON Gippstech @ Novacastrian Electronics aia a Solex @ .......... 722015
Farmer LAUNCEST Communications 447402 __ Elect.Supplies ...616055 PADDINGTON
4 Electronics... 522967 ee 315688 SHEPPARTON NOWRA Jacques er
jectronics...... z ‘. i
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= eal 316533 SWAN HILL Electronicsm.....218412 SLACKS CREEK
ichols a David Hall
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ale ne me reB05359 Se ee TOOWONG
ectronics......

FOR NEXT DAY JETSERVICE DELIVERY

BANKCARD HOLDERS— PHONE ALTRONICS TOLL FREE 008 999 007

Combine two popular projects to build

this:

Remote controlled
car burglar alarm

Protect your home or car with this unit. It
combines the UHF remote switch featured in
January with the ultrasonic alarm described in
April. Together, the two make a very effective
radio-controlled burglar alarm which is
comparable to commercial units costing
hundreds of dollars more.

by BRANCO JUSTIC

The two main components of this
project are not new. We published the
UHF Remote Switch in January 1987
and it has proved very popular indeed.
It seemed that everybody who had a

burglar alarm wanted to add UHF re-
mote control.

The Ultrasonic Burglar Alarm was
published in April 1987 and, as de-
scribed, was activated by a remote me-

All you need for a complete car burglar alarm system: main alarm module, piezoelectric
siren, ultrasonic transducers, and remote control transmitter.

60 ELECTRONICS Australia, June 1987 °

chanical switch. It is a versatile low-cost
unit that could be used as a self-
standing alarm for the home or car, or
as an ultrasonic movement detector.

The combined alarm system pre-
sented here features the ultrasonic
alarm with the added luxury of activa-
tion by the UHF remote control switch.
Some of our more experienced readers
may already be using a similar combina-
tion. The unit described here is the sim-
plest version possible in order to keep
installation simple.

In its simplest form you will only
need to make two connections to the
vehicle’s electrical system; ie, to +12V
and chassis. If you want to protect the
bonnet and boot, you may add an extra
wire and connect it to several normally
open automotive switches. Alternative-
ly, for a home system, this extra lead
could be connected to normally open
reed window/door switches.

We've also managed to eliminate the
need for an extra off/on indicator loud-
speaker. Instead we’ve wired the system
so that the existing siren/screamer dou-
bles up as the off/on indicator. This was
achieved simply by connecting the indi-
cator speaker output from the UHF re-
ceiver PCB to the siren via an isolating
diode (see wiring diagram).

For a car burglar alarm, you will find
that the receiver PCB from the remote
switch fits comfortably in the plastic
zippy case used for the ultrasonic alarm.
The best approach is to mount the re-
ceiver PCB on the lid of the case and
secure it using machine screws and nuts.
The antenna can exit through the same
slot as the transducer leads.

Some notes on the
UHF remote switch

When the UHF remote switch is cor-
rectly assembled and tuned it should
have a range of approximately 50
metres in an open field (no obstruc-
tions). Some readers have, however,
struck problems due to incorrectly in-

The remote control transmitter is small
enough to attach to your key ring.

stalled trimmer capacitors.

An incorrectly installed trimmer re-
sults in a reduced range (approximately
10cm) of operation. When using a trim-
mer which has three legs, note that the
legs opposite each other are actually

View inside the main alarm module. The PCBs should be mounted using machine screws and nuts fitted with shakeproof washers.

UHF REMOTE SWITCH RECEIVER PCB

ANTENNA
65cm INSULATED

HOOK-UP WIRE LEAVE OUT

RECEIVE
TRANSDUCER

TRANSMITTER

1N4004 DIODE
COMER WITH
PLASTIC TUBING
12v

SIREN/PIEZO
+ SCREAMER

ULTRASONIC BURGLAR ALARM PCB

TRANSMIT.
TRANSDUCER

OPTIONAL NORMALLY
OPEN SWITCHES
(BONNET, BOOT ETC.)

Fig.1: this wiring diagram shows how to combine the UHF remote control switch with the
ultrasonic alarm module. The boot and bonnet switches connected to the instant trip line

are optional.
short circuit. Only one of these legs
should be used.

Some readers also installed the three
disc ceramics in the front end in the
wrong locations. This is mainly due to
confusion regarding the coding systems

used. Note that a 330pF capacitor is
normally coded 331. Also, the decimal
point on the 3.3pF capacitor is some-
times very small.

You don’t need an oscilloscope to
align the unit. An analog multimeter

ELECTRONICS Australia, June 1987 61

SYDNEY —MELBOURNE—BRISBANE

COMM. RECEIVERS & SCANNERS

NEW BRILLIANT NRD 525
COMM. RECEIVER FROM JRC

The new NRD 525 combines advanced performance and
construction not seen on any other receiver

Features — * Wide freq. range — HF 90 KHz to
39 MHz and optional VHF/UHF band * 200
channels memory * Scan reception * Teletype
reception (optional) * Direct access tuning * Wide
dyhnamic range * Clock timer * Interface with PC

Simply The Best! only $2299

FAMOUS AR 2002

~
o
°
E
a
3
~
°
=

This unique scanner covers 25 to 550 MHz and 800
1300 MHz range. 20CH memories

NEW — ANTENNA TUNER WITH LOW
NOISE PREAMPLIFIER

ETP-1 1s an ideal accessory for all short wave receivers in
the HF band. It tremendously improves the reception of
weak stations!

CB RADIO

Emtron Ace — Australia’s
most popular 40 CH general
purpose hand held

UHF CB transceiver

APPL ICATIONS
Commercial & Professional Work
* Factory Management
* Hunting and Fishing
* Building and Road Construction
* Boating
* Farming and Pastoral
* Crowd Control
* Construction Work
* General Sport
* Surveying
* Personal Communication
Security
Business
99 Mobile and Portable

s popular model

RECEIVER ON THE MARKET

ICOM IC-R71A commercial receiver. one of the most
popular receivers among short wave listeners With 32
memories, keyboard entry, extremely high stability and
superior performance makes R71A a highly respected

3910' SPECIAL PRICE

NEW KENWOOD R5000
Just
Released

This latest addition to the respected Kenwood range of
receivers is really unique. With 100 memories, keyboard
entry, superb interference reduction and absolutely latest
technology makes R5000 the best value on the market

UNIQUE IC- R7000

ICOM IC-R7000 is a top groove sanner, with 99
memories, keyboard entry and many other features
making it an ideal monitoring source from 25 MHz to
2 GHz.

CODE CONVERTERS

For short wave listeners

In CW-RTTY-ASCII-AMTOR and FAX Mode!

To monitor marine, police. Interpol, weather, embassy.
amateur and press services!

CD 670: High performance decoder for CW. RTTY. AMTOR
(SITOR CCIR 476) and ASCII $599
CWR 860: CW-RTTY-ASCII-TOR-AMTOR Converter $459
M 800 FAX: Unique new radio Fax Converter — Ideal for
marine, weather maps, professional, commercial $1099
M 6000: A unique highly professional decoder that does
everything $1999

Full range including, EMTRON, ICOM,
ELECTROPHONE & UNIDEN

STOP PRESS

UNIQUE NEW SCANNER FROM AOR — THE
WORLD'S SMALLEST HAND HELD SCANNER
AT A SUPER LOW PRICE

AOR — manufacturers of the
famous AR 2002 have done
it again! The HX850 is a
micro with maxi features.
Bands 60-90, 118-136,
140-174, 436-512 Mhz. eM
& FM models, 20 memory
channels. Band scanning,
memory scanning, delay,
hold, excellent senstivity.

PRICE ONLY $399

VISIT OUR STORES FOR THE MOST COMPREHENSIVE
SELECTION OF RADIO COMMUNICATION EQUIPMENT

IN AUSTRALIA — COMMERCIAL,

THERE IS NO STORE LIKE
ANTENNAS:

AMATEUR AND CB.
EMTRONICS!

REGULATED POWER SUPPLIES

TEST INSTRUMENTS

KIKUSUI 60 MHz-TRIPLE TRACE
OSCILLOSCOPE — COS5060

Total Performance, multi-purpose, 3CH-Multi

| Trace. Dome-mesh type 12KV P.D.A. CRT. A
and B Alternate sweep. Hold-Off function. VERT
MODE trigger function. Energy-Saving design
(PAT. Pending). Designed for Laboratory.
Production lline, Maintenance and Field service

$1904 + tax
INCLUDES 2 HIGH QUALITY PROBES

A heavy duty and accurate scope for
service as well as production use.
Features include @ Wide freq. bandwidth
® Optimal sensitivity @ Extremely bright
display @ Auto trigger level @ Variable
hold off @ Alternate triggering @ DC
trigger coupling.

$745 + tax Includes 2 high quality probes

5MHZ OSCILLOSCOPE

GOS-955

Features

@ Low cost

@ High performance

© User friendly

@ 10mV/div Sensitivity

© Ideal for education, hobby
and service

$396 + tax

10 MHz SINGLE CHANNEL CRO $412

GOS-3310
TV sync, mode

Features
@ SmV/div sensitivity
Light & compact
Easy to operate
Low cost
Ideal for education N\
hobby and service work 4

e
e
e
@ High performance
e
e

A whole range of Lab-quality freq. counters at a
breakthrough price!

GFC 8010F (120 MHz) $276 + tax
GFC 8055F (550 MHz) $471 + tax
GFC-8100G (1GHz)

@ Microprocessor controlled

@ High resolution

@ Self diagnosis routine

$656 + tax

DIGITAL MU

GDM-8035F

@ 6 Functions (AC/DC) Voltag &
Currend Resistance & Diode
Test

@ 3% Digit

@ High resolution. 0.1mV.0 tut

@ High accuracy 0 1%

$252 + tax

Features

@ 8 digit display

@ Overtiow indicator . “
@ High sensitivity

@ High stability

GUC-2010 UNIVERSAL COUNTER $414 + tax
* From 5 Hz to 100 MNz
* Frequency, period, totalize, freq ratio and time interval

CHECK OUR RANGE OF PROFESSIONAL

MULTIMETERS
GDM 8145
GDM-8135T (GDM 8045)

@ High Voltage 1200V, 20A F
© Auto Zero Circult g o aii
©! Range: Protection @ High accuracy 0 03%
© Diode Test Function @ High range — 1200V. 200
$345 + tax @ Auto zero
@ True RMS

$462 + tax

EDM 1105A
3% digits LUD display
Diode testing

OC 0.2-1000 V. 5 ranges

100 nV max resolution, 0 8%

AC 0.2-750 V. 5 ranges

100 pV max resolution
A DC 2 mA-10 A. 5 ranges

1 «A max resolution, 1 25%

4

eee

Escort EDM 1111A DIGITAL

MULTIMETER Features
High accuracy in measuring
One rotary range switch allows
fast and convenient operation
Diode check OC/AC. 10A
Instant continuity check
Low batter indication
200 hrs long battery life
Overload protection on all ‘ ' A AC 2 mA-10 A. 5 ra
ranges wA max resolution
Capacitance measuring Ohm 200 2 - 20 Ma. 6
Transistor hFE test $83 + tax 0.1 max resolution
4 feet drop proof durability Auto zero & polarity indic ali on

ra
fe
*

15%

ANALOGUE MULTIMETERS
ANALOGUE MUILTIMETERS — SOLID PERFORMER | soLio PERFORMER — BUILT IN BUZZER

ELC-120

Stationmaster, 27 MHz base

TEIIF3J, 27 MHz ele beam

DA300. 25 MHz to 1.3 GHz scanner ant
ARASOO Active scanner ant

AH7000 Scanner discone

ANTENNA ROTATORS:

We stock all popular antenna rotators
KR 400 medium duty

KR400RC medium duty 360° dial
KR600RC medium to heavy duty
KR2000RC heavy duty

Create RC5-3 heavy duty

Daiwa MR 750 medium to heavy

We stock Australia’s largest selection of high quality
regulated power supplies
DAIWA:

PS120M — 3-15V. 12A
PS310M — 3-14 6V. 31A
ALINCO:

EP-570 — 13.8V, 6A
EP-1510 — 13.8V. 15A
EP-2510 — 13.8V. 25A
EP-3030 — 13.8V. 25A
WELZ:

RS3050 — 3-15V. 25A
RS650 — 13.8V. 6A

e®
)

$299
$549

$220
$399
$459
$549

$539
$189

CORRESPONDENCE:
BOX K21,
HAYMARKET, NSW. 2000

NSW & HEAD OFFICE:

92-94 Wentworth Ave, Sydney
NSW. 2000. TLX:AA73990
P.O. Box K21 Haymarket, NSW. 2000.
Ph: (02) 211 0988
FAX: (02) 281 1508

(Ent

EMPROMICS

Retail Division of EMONA ELECTRONICS P/L

VICTORIA:

288-294 Queen St, Melbourne
Vic. 3000.
ce from Lt. Lonsdale St)
Ph: (03) 67 8551 or 670 0330
FAX: (03) 670 0671

— BUILT
a @ 3% digit LCD display
@ Wide measuring ranges
@ 3 inputs hi. lo & guard
RANGES
Capacitance 200pF-200,uF. 7
ranges
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switched to its lowest AC voltage range,
and with a 0.1uF capacitor series with

the positive test lead, is sufficient. The-

test leads are connected between TP1
and earth on the receiver PCB.

Not all of us have access to a fre-
quency counter which is suitable for
304MHz operation and offers good
sensitivity. However, a counter is not
really needed to test the unit. Simply
set the transmit trimmer to the middle
of its travel (half mesh) and adjust the
receiver trimmer for a maximum wave-
form amplitude as measured at TP1.
Having quickly tested the unit for
proper operation, you must now adjust
the frequency to 304MHz to meet DOC
(Department of Communications) re-
quirements.

If you don’t have a counter, a cali-
brated signal generator with amplitude
modulation can be used to set the cor-
rect frequency of operation. With the
signal generator’s output lead placed in
the vicinity of the receiver, adjust the
trimmer on the receiver PCB for maxi-
mum amplitude at TP1. This done,
switch off the signal generator, activate
your transmitter (link included), and ad-
just the trimmer on the transmitter for
maximum amplitude at TP1.

Current consumption

Some readers have expressed concern
at the 100mA of current drawn by the
relay on the receiver PCB when the
alarm is switched on. This will not nor-
mally cause problems as a car battery
should be able to provide this amount
of current for hundreds of hours. How-
ever, you could strike trouble on with a
partially run down battery on a cold
winter’s day.

The way around this problem is to
wire your alarm unit to the relay con-
tacts so that the alarm is on when the
relay is off (ie, just use the other relay
contact). In this case, 100mA will be
consumed by the relay only when the

Wireless Home Burglar Alarm

As mentioned in the January
1987 issue, the UHF Remote
Switch can be used to eliminate
the wiring between the various
sensors and the control unit in a
home burglar system. This,
however, requires a _— small
modification to the transmitter
circuit so that it only transmits for
a short period of time when the
sensor is tripped.

The required modification is
quite simple and involves the
addition of a parallel 100kQ
resistor and 1000uF capacitor in
series with the positive supply rail.
Fig.2 shows the details.

Now, when the sensor contacts
close, the transmitter will only
transmit for a brief period until the
1000uF capacitor charges up.
This brief transmission is more
than enough to trigger the control
unit and ensures that the device

car is running and the battery is being
charged. However, you will now have a
long “beep” for on indication and a
short “beep” for off indication unless
R27 and R28 on the receiver PCB are
reversed.

Note that a power link was included
in the final version of the PCB between
the +12V rail and the relay wiper. With
the power link included, the relay
switches the +12V rail as per the proto-
type described in January. With the
power link removed, the relay contacts
are isolated and may simply be used as
a switch.

Finally, readers should note that, as
far as this project is concerned, the fol-

UHF
TRANSMITTER

NORMALLY
OPEN REED
CONTACTS

Fig.2: how to wire the UHF transmitter
for use in a home burglar alarm sys-
tem.

meets the required regulations.

At the end of the transmission,
the circuit draws negligible current
as set by the 100k© resistor. This
means that you can turn the alarm
off and leave a window open with-
out flattening the transmitter bat-
tery. Changing the 100kQ resistor
to 180k will reduce the quiescent
current even: further but increase
the reset time from 100 seconds
to 180 seconds.

lowing ICs are direct equivalents:
MC145026 = SG41342; MC145028 =
$G41344; 74C14 = 40106 = 4584.

Feedback on the
ultrasonic alarm

Construction of the ultrasonic alarm
is straightforward, although some read-
ers have encountered difficulties in cor-
rectly adjusting the unit.

The first thing to note is that the
transmitter frequency adjustment is
fairly critical. To adjust the unit, the
two transducers should be placed side
by side closely facing towards a blank
wall. Alternatively, they can be posi-

continued on page 129

Footnote: kits for the UHF Remote Switch and the Ultrasonic Burglar
Alarm are available from Oatley Electronics, 5 Lansdowne Pde (PO Box
89), Oatley, NSW 2223. Phone (02) 579 4985.

Fig.3a: twin core shielded cable must be used to wire the trans-

mitter for maximum drive.

—_<—_
RECEIVE
TRANSDUCER

NC

@\c

INO POWER SIREN +
@|+12v

INSTANT INPUT
GROUND

+
TRANSMIT
TRANSDUCER

INC
lc
INO POWER SIREN +
+12V
@ | INSTANT INPUT
@ |crounp

Fig.3b: how to wire the transmitter for reduced drive. Single core

shielded cable can be used here.

ELECTRONICS Australia, June 1987 63

Circuit & Design ideas

Interesting circuit ideas from readers and technical literature. While this material has been checked as far as possible, the circuits have not —
been built and tested by us. As a consequence, we cannot accept responsibility, enter into correspondence or provide constructional details.

ALL DIODES 1N4001

Quiz game
adjudicator

This circuit was designed as a quiz
game adjudicator and is used as a teach-
ing aid for children.

The circuit uses a single quad NOR
gate IC, four transistors and 12 diodes.
ICla, b & c are wired as inverters with
one input of each gate connected to
ground. When a contestant presses a
button (S2-S4), the remaining input of
the associated NOR gate is pulled high
and thus the output of the gate goes
low.

This low output does three things.
First, it inhibits the other two gates so
that pressing the other two buttons has
no effect. Second, it turns on an associ-
ated PNP driver transistor (Q1-Q3) via
a 2.2kQ resistor to light one of the
LED displays. And third, it momen-
tarily turns on Q4 via inverter IC1d and
timing circuit C4R8 to operate an elec-
tronic buzzer for approximately two sec-
onds.

Finally, pushbutton switch S1_ dis-
charges the 47uF capacitors C1-C3 to
reset the game. Construction of the cir-
cuit is not critical and the pushbutton
switches can be mounted inside 35mm
film canisters.

D. Harvey,

Stanthorpe, Qld. $20

Screecher protection
for bonnet and boot

While the Screecher car burglar alarm
(EA, August 1986) is marvellous for
protecting the passenger compartment,
it offers no defence against the thief
who attacks the boot or engine areas.
The solution is obvious — simply add
extra sirens to protect these areas and
trigger them by means of normally open
switches.

The accompanying circuit shows the
basic scheme. Switch SI from the origi-
nal circuit now controls the additional
siren circuits as well as the main alarm.
This means that the peripheral alarms
only operate when the main alarm is
on. Diodes DI and D2 provide isolation
for the peripheral sirens so that the
boot and bonnet lamps can be used in-

i)

64 ELECTRONICS Australia, June 1987

TO ALARM
INPUTS

dependently of the alarm system.

In most cases, you will be able to
make use of the existing boot switch, al-
though a bonnet switch will have to be

fitted. The bonnet lamp can be left out
of circuit if not required.

R. Hicks,

Pennant Hills, NSW. $10

Magnetic pickup for
digital speedometer

This simple circuit shows how a mag-
netic pickup may be used to replace the
optical sensor in the digital speedometer
(EA, January 1987, page 60). It consists
of four magnets, a pickup coil and a
BC548 transistor (Q1).

Here’s how the circuit works: The ro-
tating magnets induce a series of pulses
in the pickup coil and these are coupled
via C1 to the base of Q1. QI is nor-
mally just biased off by R1 and R2, but
turns on briefly each time a pulse is re-
ceived. The resulting pulse train pro-
duced at Q1’s collector is then gated
through IC1la to the CLK input (pin 12)

TAIL SHAFT

MAGNETS

FROM PIN3,
Ic2

of IC3.

The coil consists of 200-300 turns of
0.4mm enamelled copper wire, about
20mm in length, wrapped onto a 2BA

bolt. The rest of the circuit operation is
as described in the January issue.

M. Duperouzel,

Beckenham, WA. $1 0

Transistor tester add-on
for multimeter

Transistor test circuits generally seem
do to little more than can be achieved
with a multimeter. The circuit shown
here improves on that described by D.
Shawcross (EA, July 1982) as it can
identify the emitter and collector leads.
This is important if you mostly use recy-
cled transistors and have no data on
their pinouts.

To use the device, the base lead must
be known and correctly connected. The
connections to the other two leads don’t
matter, and the ohmmeter can also be
coupled without regard to polarity.

The first test step is to obtain the
typical “diode” reading by trial and
error using the polarity switch. Once
this has been done, the pushbutton is
pressed and the reading noted. If the
resistance increases by about 12-20%,
the selector switch indicates the emitter;

TO
MULTIMETER

if the change is only of the order of
2-5%, the selector indicates the collec-
tor.

Note that the above is only valid if

the transistor is OK. Abnormal readings
indicate a defunct transistor,

A. Corben,

Lillian Rock, NSW. $10

Dual rails from 01

a single battery PLT,
1k )
5

power an op amp project from a single
rail power supply but could also be used
to power other appliances which require
plus and minus supply rails eg, the =
Technics SLP-X7 CD player which re-
quires +6V.

The circuit is based on a 555 timer IC
oscillator driving a complementary
NPN/PNP transistor stage. Cl, R1 and

This circuit was originally designed to
eg

1N5404

R2 set the oscillator frequency to 1kHz
and the square wave output at pin 3
drives QI and Q2 via 1kQ current limit-
ing resistors. Q1 and Q2 thus alterna-
tively switch on and off and this switch-
ing action causes C3 and C4 to charge

via D1 and D2 to +12V and -12V re-
spectively.

These voltages are then applied to
positive and negative 3-terminal regula-
tors. The 5kQ trimpots allow each rail
to be independently adjusted to the de-

sired output voltage (up to +9V and
-9V). Note that Ql, Q2 and the two
3-terminal regulators should be pro-
vided with adequate heatsinking .

$20

J. Webb,
Maryborough, Vic.
ELECTRONICS Australia, June 1987 65

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OU 0 ©

The Serviceman

When skies are grey, Sony Boy

At what stage of its existence should a TV set — or any
appliance for that matter — be considered to be beyond
economical repair? Age alone need not necessarily condemn
it; it is merely one of several factors which would influence a
decision. And even then there is a good deal of luck involved.

This is not a new theme in these
notes, but it surfaced again recently
when I rescued a couple of sets which
might otherwise have been on their way
to the tip. More particularly, it was
prompted by what appears to be an un-
fortunate tendency on the part of some
of my colleagues; a tendency to become
“tip-happy”, whereby any set which ex-
hibits an unusual fault and/or is one
with which they are not familiar is con-
demned as being beyond repair and fit
only for the tip.

More specifically, the present story
concerns a number of Sony Model KV-
1830AS and KV-2000AS colour sets,
these being 46cm and 51cm versions re-
spectively, but using virtually the same
chassis. I last dealt with one of these
sets in the January 1986 notes and men-
tioned at that time that there seemed to
be an aversion to these sets on the part
of some servicemen.

That was a fairly general statement,
but the latest episode produced much
more specific evidence that this is a very
real problem. At one stage I had no less
than seven of these sets through the
workshop in quick succession. Only two
were from regular customers, while at
least two had bounced from colleagues
in the district. The remaining three
were also new customers and I have
good reason to suspect that they had
had similar experiences and had learned
by word of mouth that I would at least
take the job seriously.

Set number one

But let’s start at the beginning. The
first job was from one of my regular
customers and, while a little puzzling
technically, did not involve any other
sort of hassles. However, it will help to
acquaint the reader with the “feel” of
the set.

68 ELECTRONICS Australia, June 1987

The primary fault was simply that the
set had shut down, and J didn’t expect
that this would present much of a prob-
lem. However, the owner had ap-
proached me on a previous occasion,
when visiting the shop, regarding what
he described as “ lines on the
screen”. Closer questioning revealed
that they were vertical lines, which he
further described as being “.. . all
over the screen”. I must admit that the
“all over” puzzled me, and I simply
suggested that he bring it in for me to
see. In the event, it took the total fail-
ure to get it on my bench.

The most likely cause of total shut-
down in these sets is failure of the SCR,
Q901 (SG613), in the horizontal output
stage, and it doesn’t take a genius to
find this and fit a new SCR, even the
first time. Sure enough, a simple check
confirmed that the SCR was shot, and
fitting a new one brought the set back
to life. So what about the “. . . vertical
lines all over the screen”?

In fact, there were vertical lines, but
they weren't all over the screen. They
were quite prominent on the left hand
side, becoming progressively weaker to-
wards the right, and virtually invisible
halfway across. In short, a classic case
of ringing in the horizontal output
stage. Unfortunately, having diagnosed
it that far, I could make no further sug-
gestions because I had not encountered
that fault in this set before.

I fished out the manual and turned to
the “E” board diagram. Tracing the
135V rail from Q901 up to pin 16 of the
horizontal transformer, T801, I was re-
minded that a diode connected to this
line, D806, has a reputation for going
short circuit and shutting things down.
And, while the symptoms didn’t fit this
possibility, I did wonder what a partial
breakdown might do.

But I didn’t speculate on this for long
because the next thing I noted was an
inductor in the line, L805, 3.3uH,
shunted by an 180, 2W resistor, R812.
I’m not sure of the inductor’s role, but I
imagine it is a linearising device of some
kind. More to the point, what was the
shuntin resistor’s role? Since resistors
are often connected across inductors to
provide a damping action, I wondered
what would happen if R812 was open
circuit.

Well, I'd picked it in one — except
that the resistor was not open circuit,
but had jumped from 18Q to around
170Q.. Why, I can’t imagine. Anyway, I
replaced it with an 180, 5W resistor
which was the nearest I had. There was
plenty of space and I reasoned that the
extra rating would do no harm. And
that fixed it; the set was as good as
new.

Set number two

The next set belonged to someone |
had not seen before. Again there was a
primary fault which was shutting the set
down, plus a secondary fault which was
spoiling the picture. But there the simi-
larity ended because the nature of the
secondary fault, and its history, were
both quite different.

The customer introduced himself by
explaining that he had previously had
the set serviced by a colleague whom I
shall call “Joe”. Now I know Joe rea-
sonably well and he’s a nice enough sort
of bloke at a social level. He’s probably
also very kind to his mother and all that
(makes sure she has adequate illumina-
tion at the wood heap) but his approach
to servicing — and particularly his ap-
proach to servicing Sony receivers —
leaves a great deal to be desired.

Basically it seems that Joe, along with
at least one other colleague, has a bias
against the Sony sets. The only reason
for this seems to be the fact that these
sets are a little different — even uncon-
ventional — compared with a lot of
other sets and, for some reason or
other, these fellows seem unable to
make the transition to a different ap-

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This diagram shows portions of the ‘‘D”’ and ‘‘E’’ boards in the KV-1830AS and KV-2000AS Sony receivers where two of the faults oc-

curred. A third fault was on the ‘‘F’’ board.

proach. This is surprising when one con-
siders that most set designs are unique,
and can often present quite a challenge
at first encounter. But that’s all part of
the game.

Anyway, that’s the broad back-
ground. In greater detail, this custom-
er’s story went something like this: on
the last occasion he had taken the set to
Joe it was suffering from two faults: one
main fault which caused a complete fail-
ure; and a second which caused a severe
bowing or pincushion effect to the sides
of the picture.

Joe fixed the main fault (whatever it
was), but did nothing about the pin-
cushion problem. When the customer
pointed this out, Joe insisted that it was
a major problem with these sets and
could not be fixed. Then he went on to
berate Sony sets in general, claiming
that parts were hard to get, were too
expensive, and that the sets were never
much good anyway. He rounded this all
off by suggesting that, the next time it
failed, the customer should send it to
the tip and buy himself a new set. And
he made it clear that he didn’t want to
see the set again.

With this advice ringing in his ears,
the customer took the set home and, for
the next two months, put up with the
badly distorted picture. Then it com-
pletely failed again, which is how it
ended up on my bench.

The owner was apparently clutching
at the straw of a second opinion in the
faint hope that a repair might still be
possible, but clearly not very confident
that it would be. He was as much con-
cerned about the pincushion effect as he
was about the total failure because, as
he put it, there was little point in get-
ting the set going if this could not be
fixed; he simply could not tolerate

watching such a grossly distorted picture
any longer.

Well, the total failure was no prob-
lem; it was another Q901 SCR failure,
so it took only a few minutes to get the
set running again. It was only then that
I realised just how bad this bowing ef-
fect was and could only wonder how the
owner had put with it for so long. It
wasn’t exactly the same as a true pin-

\y 0610 0612
\ S34 (Te
UB RECT=1 KICK RECT B+ RECT

Relevant section of the Sony ‘‘F’’ board. A simple fault is sometimes hard to find.
ELECTRONICS Australia, June 1987 69

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The Serviceman

cushion, since it was mostly on the
sides, but the difference would have
been purely academic from the custom-
er’s point of view.

Unfortunately, I didn’t have a clue as
to the cause, never having seen the ef-
fect before. All I could do was go to
what seemed like the most appropriate
part of the circuit and play it by ear.
This was the “D” board which contains
the vertical and horizontal oscillators,
the vertical drive and output stages,
horizontal drive, and the convergence
circuitry and controls. The horizontal
drive from this board goes to the previ-
ously mentioned “E” board and the
Q901 horizontal output stage.

A preliminary check with the CRO
brought me to a combination of two
transistors, Q512 and Q513, described
as “PIN AMP-1” and “PIN AMP-2” re-
spectively. I sensed there was something
wrong here, and this was confirmed
when I made some voltage measure-
ments and found that they were nothing
like those quoted on the circuit.

I also realised something else while
making these checks; someone else had
been to this part of the board before
me, and the copper side was in pretty
much of a mess. In fact it appeared that
almost every component — resistors,
capacitors, transistors etc — had been
removed and refitted or replaced at
some stage. I spent some time cleaning
up the copper side before I could be
reasonably sure that there were no dry
joints, fractured tracks, or solder slivers
fouling things up.

I first suspected the transistors, so I
pulled them out and checked them but
drew a blank. As far as I could tell they
were well within tolerance. So what was
upsetting the voltages. There are two
preset pots in this part of the circuit:
VRS509, a 3kQ unit designated “PIN-
.AMP”,, and VRS508, 1 10kQ unit desig-
nated ““PIN.BIAS”’.

It was the latter unit which caught my
eye because it obviously formed part of
the base bias network for Q512 and, if
it was faulty or incorrectly set, it could
upset all the voltages in this network.
So what would happen if I varied it?
Taking the precaution of connecting a
couple of meters to vital voltage points,
I attacked it with a screwdriver.

In fact, attacked is hardly the right
word because I had barely touched it
when everything came good; the volt-
ages snapped into their correct values
and, more important, the bowing van-
ished completely. The fault was nothing

more than a dead spot on the pot — it
was as simple as that. I fitted a new
pot, set it up according to the manual,
and the set was as good as new. The
whole operation had taken me about
half an hour.

So why had Joe been unable to find
it? Granted, I had had to find my way
around the circuit to these two transis-
tors but then, if the state of the board
was anything to go by, Joe had finished
up there too. So why the “... major
fault that could not be fixed’ routine?
Frankly I don’t know, but it is a pretty
scathing indictment of Joe — and any-
one else like him — when they con-
demn a set to the tip for such a simple
fault.

Needless to say, the customer was
both surprised and delighted at the re-
sult. In fact, he could hardly believe it.
He stood looking at the picture for sev-
eral moments and then, as if trying to
convince himself that something impos-
sible had happened, remarked, ‘‘You’ve
actually been able to fix it!”

It was almost worth fixing for that
comment alone.

The only criticism I can level at this
Sony set — and it is a minor one — is
that a number of preset pots on the
“D” board carry designations which are
rather puzzling, or even confusing in
some cases. VR509, for example, is
designated “PIN.AMP” which I take it
means “‘pincushion amplitude”. In fact,
it acts more like a width control, this ef-
fect being quite substantial, while the
effect on pincushion distortion appears
to be minimal.

Similarly, VRSO0S “HOR.AMP”
(horizontal amplitude) appears to have
more effect on convergence than any-
thing else. And VR507, designated ““Y
BOW”, which I assumed might be a
pincushion adjustment on the “Y”’ axis,
also appears to be mainly a convergence
adjustment.

But confusing designations of this
kind are nothing new in this game, and
certainly not peculiar to the Sony sets.
When it comes to the crunch one often
has to find out what particular control is
supposed to do by simply observing
what it does.

Set number three

The next Sony set belonged to one of
my regular customers and is interesting
only in the technical sense. The owner
had originally contacted me with the
complaint that the set would sometimes
not function at switch-on, but would

usually come good at the second or
third attempt, but with a substantial
waiting period in between.

I had called in to look at the set while
making calls in the vicinity but, typical-
ly, it refused to misbehave on demand.
And, since the owner wasn’t keen to
put it in for service at that time, we
agreed to leave it and see what hap-
pened. I heard nothing more for a cou-
ple of weeks, then he was on the phone
with the news that the set had failed
completely. And so it finished up on the
bench.

I pulled the back off, made a cursory
inspection for any obvious damage and,
finding nothing, switched the set on.
And, just to make it harder, it fired up
immediately. Since it was obviously
going to be cranky I decided to monitor
some of the vital voltages while it was
running, and thus provide a reference
for when it failed.

My first check point was the HT rail,
and I struck oil immediately. This nor-
mally runs at 135V but was actually up
to 149V. This seemed the most likely
explanation for the failure to start, since
the power supply will normally shut
down at somewhere near this rail volt-
age. On this basis I turned my attention
to the power supply (‘“F’’) board.

More particularly I went to the 135V
adjustment pot, VR601 (2.2kQ), feed-
ing the base of error amplifier Q601.
The rail voltage responded immediately
to this adjustment and I was able to
bring it back to 135V. I didn’t imagine
for one moment that this was going to
be the answer, but I wanted to see what
happened.

I let the set run for about 15 minutes,
while monitoring the HT rail, by which
time the voltage had dropped to 123V. I
reset it to 135V and let the set run for
an hour or so, during which time the
voltage remained stable. Then I
switched it off, left it for an hour or so,
and switched it on again. And I wasn’t
really very surprised when the voltage
shot up again, nudging 150V.

I repeated this ritual several times
and on a couple of occasions the voltage
went over the 150V mark and the set
refused to start. Well, at least I knew
what was happening, even if I didn’t
know exactly why. But, based on previ-
ous experience, there were several com-
ponents which needed to be checked.
(Readers would be well advised to refer
to the January 1986 notes for a list of
some likely power supply faults).

Transistor Q604 is a common of-
fender in regard to erratic HT voltage,
as is electrolytic capacitor C612, a

ELECTRONICS Australia, June 1987 71

The Serviceman

3.34F which was the main culprit in the
January story. I replaced both of these
components and put the set through an-
other cycle, but drew a blank; the fault
was still there. Another suspect was the
previously mentioned error amplifier,
Q601. I first tried spraying it with
freezer and when this had no effect, I
replaced it. But, again, no joy.

I also removed and checked transis-
tors Q602, 603, 605 and 606. As far as I
could tell all were functioning correctly.
After all that highly scientific approach
(ahem!), the manner of the ultimate
solution was something of an anti-
climax. I had left the set running for
some time and decided to remove the
“F” board for a closer examination, just
in case there was a visual clue.

Well, there was a clue all right, but it
was tactile rather than visual. As I han-
dled the board I became aware that a
part of it was quite warm. This led me
to C620, a 33uF, 160V unit on the main
HT rail — and it was more than warm,
it was hot! Well, that was enough for
yours truly; I pulled it out and fitted a
new one.

Needless to say, that fixed it. I reset
VR601, then put the set through several
cycles of lengthy on and off periods,
during which the HT rail remained
within a fraction of a volt of its assigned
135V value. I considered the point
proved and returned thé set ot the cus-
tomer.

But I must confess to being puzzled
as to why the capacitor caused the set
to behave as it did. I checked the ca-
pacitor and found that its value had
dropped to about 20uF, while its leak-
age was quite high. But why did it allow
the rail voltage to go high at switch-on?
The only theory I can advance is that its
leakage was low when it was cold, but
increased substantially when it was hot.
Also, I suspect that it had always exhib-
ited this characteristic, to some extent,
even when new.

Assuming that VR601 was originally
adjusted when the set had been running
on the bench for some time, it is likely
that it was set too high for the cold
condition. This may not have mattered
at the time, with the cold leakage being
high enough to hold the rail voltage
below the critical point at switch-on.
However, with the passage of time, and
loss of capacitance as the capacitor
dried out, it is likely that the cold leak-
age would become less, thus allowing
the voltage to rise to the shut-down
point.

72 ELECTRONICS Australia, June 1987

I know all that relies on a lot of as-
sumptions, but it is the best I can sug-
gest. If anyone has any other ideas

Set number four

The next set was another one that
had bounced, this time from a colleague
conveniently referred to as “Jack”’. Ear-
lier, I suggested that Joe’s attitude to
servicing in general, and to Sony sets in
particular, left a lot to be desired. With-
out retracting that comment in the
slightest degree I can only say that,
compared to Jack, Joe is a paragon of
serviceman virtues.

Jack is .what some people would
euphemistically refer to as a “character”
or, if he was very wealthy, as “‘eccen-
tric’. Most people, and particularly
those who have crossed him, would
probably use a more realistic, down-to-
earth, Australian expression. In more
precise terms, Jack is one of those peo-
ple who is never happy unless he is mis-
erable and, to boot, suffers from a vio-
lent temper.

If Jack is having a bad day — ie, is
chasing a stubborn fault — he is com-
pletely unapproachable. One potential
customer, who wanted to make a minor
purchase, discovered this to his cost
when, after waiting patiently at the
counter for some time, he had the te-
merity to suggest that Jack might leave
what he was doing and attend to his
wants.

Snarling, “‘Can’t you see I’m busy”,
Jack erupted from the workshop, leapt
over the counter, seized the customer
by the arm, and forcibly ejected him
from the shop. When the unfortunate
victim related this story to me he was
able to show me the bruises on his arm.
At the time, he was seriously contem-
plating taking legal action, but he later
decided that it wasn’t worth the hassle.

Well, that’s some of the background
on Jack.

And, as I intimated earlier, he also
hates Sony sets. In rejecting the set
which came to me, Jack had turned on
a real tantrum. According to him, these
sets are no adjectival good, you can’t
get parts for them, there is no service
data available for this model, and they
were only a load of rubbish in the first
place. Then, “Take it away, I don’t
want to see it”.

Which is how it finished up on my
bench.

Now I don’t carry any special brief
for Sony, any more than any other
brand, and I will criticise a model or

firm if I feel it is justified, but those
statements are demonstratively untrue.
Granted some parts may be a bit hard
to get from time to time, but this prob-
lem is by no means unique to Sony. As
for service data, I have had no difficulty
in obtaining whatever information I
need. As for the ‘load of rubbish” —
well, I just don’t agree; the Sony sets
are as good as any.

Anyway, enough of that. The real
clincher was the nature of the fault now
on my bench. Would you believe it was
the same pincushion-like fault which
had floored our friend Joe, and only the
second one I had ever seen. Needless to
say, I was able to fix it in short order,
much to the surprise and delight of the
owner. I have no doubt I have scored
another loyal customer.

And those are the main Sony stories.
There were actually three more sets
through the workshop at this time, all
belonging to new customers, but none
was particularly noteworthy in either
the technical or historical sense. I men-
tion them only because, as I intimated
earlier, I suspect that they came to me
as a result of word-of-mouth advertis-
ing.
And that’s the best kind.

But the real point of these stories is
the fact that, using only ordinary test
equipment, and ordinary servicing tech-
niques, I was able to find and fix three
faults which were all new to me. and
this in a brand and model of set which
Joe and Jack insist is too hard to ser-
vice.

Something doesn’t add up some-
where.

Time delayed faults

To change the subject, in the March
notes I commented that I had not been
able to find anyone who could explain
exactly what mechanism one would em-
ploy to create a time delayed fault; a
practice supposedly employed by serv-
icemen in general to boost business —
and profit.

Well, I would stick my neck out and
Mr P.T. of Clontarf, Queensland has
applied the verbal axe. He writes:

Towards the end of the monochrome
TV era there was a bargain TV mainten-
ance contract available for a mere $10
per year. If service was required the cus-
tomer paid a flat rate of $10 per service
call. The $10 premium went to the com-
pany and the call fee went to the service-
man.

Towards the end of the monochrome
TV era there was a bargain TV mainten-
ance contract available for a mere $10
per year. If service was required the cus-

tomer paid a flat rate of $10 per service
call. The $10 premium went to the com-
pany and the call fee went to the service-
man.

This created an incentive on the part
of the serviceman to make as many calls
a day as possible, with 12 jobs a day
being regarded as normal. Unfortunate-
ly, it also tempted unscrupulous service-
men to help things along by making the
faults more predictable; by always carry-
ing a pocket full of 1A fuses.

The average set was equipped with a
2A mains fuse so, after repairing a fault,
a new 1A mains fuse would be fitted
whether it was needed or not. Usually
the lighter fuse would hold up for a cou-
ple of days, or up to a week at most.

If he was a smooth talker the service-
man was even praised by the customer
by knowing how to find the “fault” so
quickly! And he scored another $10 for
five minutes’ work. Under this scheme
the serviceman paid for his own parts (a
6CM5 or a 6AL3 cost about $3) and he
did not get a call fee for jobs requiring
workshop attention. Tube brighteners
were often used. Since people are
generally suspicious, and bad news is al-
ways popular, it is quite likely that ru-
mours of this practice have endured, and
travelled. It takes only a few such prac-
tices to be revealed and we all get tarred
with the same brush. Why should we all
have to bear the bad will created by a
minority.

Thank you, P.T., for that little bit of
informative history. I admit I hadn’t
heard of it before, but let’s hope it is
history. These days most servicemen
who value their business would never
think of resorting to such tactics, and
most of them would make some kind of
a concession in the event that a set
bounced within a few days, regardless
of the actual cause. That’s about all we
can do to build up public confidence
and goodwill. ®@®

TETIA Fault of the Month

AWA G Chassis

Symptom: Picture starts with exces-
sive brightness, low height, vertical
foldup and no 150V rail. Picture
then fades as set warms up, leaving

only bright white screen.

Cure: R581 (4.70 0.5W watt fusi-
ble) open circuit, or break in track
to plug EC. This fault was found
while repairing damage done by a
dry joint under C571, the yoke iso-
lating capacitor.

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THREE TERMINAL REGULATORS

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RTA 149. QP. 106 A

ELECTRONICS Australia, June 1987 73

Literature

Data Communications

DATA COMMUNICATIONS, NET-
WORKS, AND SYSTEMS: by Thomas
C Bartee, Editor-in-Chief. Published
1985 by Howard W. Sams and Co., Inc.
Indiana. Hard covers, 260 x 200mm, 359
pages. Illustrated with diagrams. ISBN 0
672 22235 3. Recommended retail price
$75.

This book covers the areas of data
communications, networks and systems.
As such, it covers such topics as local
area networks, protocols, network se-
curity, error control, modems, multi-
plexers and concentrators, gives a gen-
eral review of transmission media and
looks at common carrier regulation in
the USA.

The text is aimed at engineers, system
managers, and technicians and brings
together a great deal of material on
data communications which has previ-
ously been hard to come by. There are
ten chapters in all, each prepared by an

expert in the associated field. At the
beginning of each chapter there is an in-
troduction to the author and then a
brief review of the subject before it is
treated in detail.

Each chapter ends with a lengthy list
of references suitable for readers inter-

ested in following up a particular area
of interest.

The first chapter is on Transmission
Media and discusses open wire lines,
paired cable, coaxial cable, waveguides,
optical fibre and radio. The following
chapter on Carriers and Regulation is
mainly relevant to the USA market.
Modems, Multiplexers and Concentra-
tors are covered in chapter 3, while the
important subject of Protocols is cov-
ered in the next chapter.

The next three chapters are devoted
to PBX, Baseband and Broadband
Local Area Networks in that order,
while chapter eight is on Computer and
Communications Security and includes a
major portion on encryption. The last
two chapters are on LAN standards and
Error Control.

This is an excellent reference book
for engineers working in this field and
covers a broad field with detailed infor-
mation. Our review copy came from
Jaycar Electronics. (L.D.S.)

Semiconductor Physics

RATE EQUATIONS IN SEMICON-
DUCTOR ELECTRONICS: by J.E.
Carroll. Published 1985 by Cambridge
University Press, Cambridge. Hard
covers, 234 x 157mm, 177 pages. Illus-
trated with diagrams and equations.
ISBN 0 521 26533 9. Recomended retail
price $74,

This text concentrates on the dynamic
behaviour of semiconductors rather than
the steady-state approach which is nor-
mally taught. It is intended to give engi-
neering students a far greater insight
into the behaviour of semiconductors
and optoelectronics. This is important in
view of the ever increasing demand for
faster devices and circuits.

As might be expected, such a text is
full of mathematics which will probably
discourage the casual reader but the au-
thor has gone a long way to make his
material as readable and relevant as
possible.

Chapter | is an introduction to rate
equations as they apply to everyday
events such as traffic flow, chemical

74 ELECTRONICS Australia, June 1987

reactions and buying and selling houses.
The example involving houses revolves
around A. N. Electron who, if he sells
his house, leaves a hole suitable for
potential buyers to fill!

Further chapters move on to elemen-
tary rate equations in semiconductors

Rate equations
in semiconductor
electronics

JE.CARROLL

concerning mobility and recombination.
Rates of switching follows and includes
the Schottky barrier diode, the FET and
bipolar transistor. Rate equations are
also covered for quantum electronics,
optoelectronics and transfer in phase
space.

Maxwell’s equations are introduced in
chapter 7 for photon rate equations.
This is to show how quantum and the
classical concepts are unified.

Appendix A is on Counting States,
while appendix B covers the differences
between gas and diode laser rate equa-
tions.

Each chapter includes several ques-
tions to ensure that the material cov-
ered in the chapter is understood. Solu-
tions are at the rear of the book.

Overall this book is not for the light
reader and can be regarded as heavy
going. Still, it does present a new ap-
proach to semiconductors and could be
very useful as a :eference or text for
physics and engineering students.

Our copy came from Cambridge Uni-
versity Press 10 Stamford Road Oak-
leigh Melbourne, Vic 3166. Ph (03) 568
(322. (J.C.) @

Meter valued at $29! cous

The $100
Yaesu bonus offer!

You won't believe your luck! The incredible Yaesu
FT-209RH 2 metre hand-held is now better value than
ever. With every FT-209RH sold we're giving away a
FREE battery valued at $98.90!! Yes, you can now
have all the features and quality of Yaesu at the
lowest price ever! With up to 5 watt output (3.7W with
FNB3 battery) 10 memories (it even remembers the
repeater split), keyboard entry for everything, huge
range of scanning options and much, much more!

fim 599

FNB-3 NiCad Battery valued at *98”

Cat D-3506

Just what your mobile needs! The PA-3_ The perfect way to check the power

Car Charger is intended for operating
10.8 volt transceivers from a car
cigarette lighter socket. Includes
charging as well as power and now it’s
BELOW COST!! Suits FNB-3 pack as

output of your hand-held — anywhere
between 6 metres and 70cm!! Famous
Welz brand so you know it's quality.
Simply replaces your antenna and you
get a direct readout of power!

Cat Q-1343

Huge Amateur $avings all this month!

We realize that you amateurs are a
bright lot and we'd hate to see your
base stations zapped out. So here’s a
great value station protector! The Welz
Coax Lightning Protector. Fits easily to
your antenna system and it'll absorb
that surge if your antenna gets zapped!
Cat D-5210

COAXIAL LIGHTNING
SURGE PROTECTOR

ony $4,985

It's BELOW COST! The Yeasu YM24A
Speaker Mic. An 8 ohm speaker and
2k microphone all rolled into one! The
6 pin plug suits all FT207/FT208
transceivers and the mounting bracket
is attached to the mic. Cat C-1111

This'll make life easy! Suits all Yaesu
transceivers with scanning function.
Has 8 pin plug for easy hook up and
the compact design make: .t easy to
hold for long periods. 500 onms
impedance. Cat C-1116

Here’s value! The MMB-21 Mobile
Bracket to suit the FT-203/209/709
transceivers — and it's “2 PRICE!!
Saves your equipment slopping all
over the car and saves you money to
boot. But hurry, they can't last forever
at this LOW price! Cat D-3501

WAS $29.95

now °4 495
VY PRICE!!!

well as older style transceivers.

, A int
Cat D-2899 We've done it again! The MMB20

mobile bracket is designed specifically
for the FT757GX. Allows mounting in
either standing or slung position with
three different mounting angles!

Cat D-2949

JUST

$995

This Power Meter FREE with all hand-helds
sold this month!!!

SS WAS $54.95
See Ny $29"

NOW ONLY eon

¥

Take a bow Yaesu! The FT767GxX is everything when it

comes to transceivers. If a transceiver could get up and dance this
one would be the Prima Ballerina! The very latest in technology so
you can drag in those illusive signals or to make sure your signal is
heard above the QRM. All modes on ALL amateur bands,
continuous coverage triple conversion superhet receiver, built-in
automatic antenna tuner, die-cast aluminium and ducted cooling
giving an incredible 30 minutes output at full power and much,
much more! Try Yaesu at DSE — the advantages are easy to see!
Cat D-2935

Specifications

Receiver: 100kHz to 29.9999MHz, 50 to 53.999, 144 to 147.999,
430 to 439.999MHz

Transmitter: All WARC bands to 30MHz, VHF and UHF as above.
Output: 100W (AM 25W carrier) on HF, 10W (2.5W AM) VHF &
UHF

Antenna Impedance: 20-100 ohms HF (nominal 50 ohms),

50 ohms UHF/VHF

Emission: J3E, A1A, J1B, A3E, F3E

Sensitivity: 0.25uV (SSB/CW/FSK, 1.5-450MHz, 10dB stn/N)

“We all know that the world’s best selling Electronics Kits
are from HEATH KIT. a8 "Jack O’Donnell — Managing Director, Altronics.

The Digital Weather Computer displays everything from
wind chill factor to indoor/outdoor temperatures, to wind
speed and direction with accurate 16-point compass
resolution. It even has microprocessor controlled memory
for data storage by date and time! Yes, you can compare
minimum and maximum readings from indoor temperature
to peak wind gusts. No sports or outdoor person should be
without one! But what's best is; You can build it yourself!
FEATURES:

® Digital clock/4 year calendar. © Four digit accuracy. ©
Barometer. e Thermometer. ® Wind vector. ° Memory. ©
Compact size. ¢ Solid oiled walnut cabinet. Cat G-2000

WAS $1100 $
NOW

: S . SSAVE OVER $100

Hero Jr is the most advanced robot
we've ever seen — and you can build
it yourself. A great way to learn
about the future. Hero Jr is
preprogrammed, it'll wake you up,
remember all those things you keep
forgetting (like anniversaries, etc.)
Program Hero Jr with its own keypad
or with your home computer". It's
battery operated and right now we're
giving a FREE M-1156 transformer
with every Hero Jr sold. You'll SAVE
$69.95. Cat G-1005

Economy plus! A quality piece of test
gear that’s essential for all audio and
digital circuits. 10Hz to 100kHz range
with both sine and square wave
output. Battery operated (not
supplied). Cat G-4010

Route up to 4 antennas or
interconnecting equipment at the
touch of a dial. Switch from one RF
source to any other while grounding
all outputs not in use. Handles 2kW
PEP. Build it in a night! Cat G-3010

Ideal for on-air testing without any
RF escaping (ya gotta watch those
sneaky little RFs). 1kW dummy load
in a 4 litre can with less than 1.5:1
VSWR up to 450MHz. (Transformer
oil not supplied) Cat G-3015

459%

* With optional
accessories

Here's value and quality — all rolled
into one! Modulated and un-
modulated signals from 310kHz to
110MHz with calibrated harmonics to
220MHz. Hobbyist or technician —
you can't do better! Cat G-4005

A must for all hobbyists and
technicians! Don’t throw out those
old unmarked components. Check
them with this R-L-C bridge. Build it
in about 4 hours! Resistance; 10
ohms to 10M. Capacitance; 10pF to
10uF. Cat G-4025

Clean virtually anything ultrasonically
— without abrasion — components,
jewellery, coins...even dentures! With
150mm x 100mm tank you can
professionally clean those precious
items without fear of damage. (not
suitable for pearls or turquoise)

Cat G-2010

Requires
115V

‘299

Anyone who works with FM will
appreciate this! Quickly; and
accurately measures deviation from
2 to 75kKHz over the range 25 to
1000MHz. Can be used in-line for
continuous readings or used as a
portable ‘in-field’ test unit! Cat G-4000

Transformer

Ideal for schools, clubs, colleges,
etc. The Laser Trainer is the perfect
way to learn. Uses a HeNe gas laser
to generate intense coherent light. It
even includes receiver/monitor for
measuring signal strength and built-
in amplifier for sound transmitted
over the laser beam! Cat G-2020

Requires 115V Transformer

Our M-1156 stepdown transformer is
ideal for powering many of the
Heathkit projects and it’s amazing
value! With 240 volt input and 60VA
capacity. Fitted with US style two pin
socket and fully enclosed for safety!

Cat M-1156
69%

A New Ag

ein “¢

Photocopying

Totally portable photocopying is now a reality! The
Sharp Z-HC1 Handy Copier is here. At about the size of
a paperback book the Handy Copier will go anywhere.
With the revolutionary pen-style scanner you can
selectively copy an entire text or any part you need.
Even gives enlarged copy and graphics mode! Fantastic
for students, journalists, engineers...anyone!

Cat V-5000

oNLy °399

Listen to the
world

The '87 edit. of World Radio
TV Handbook gives you a
complete listing of
international radio and TV
stations. Everything that's
worth listening to and more

esse SOS
Giant
Handbook of
Electrical
Circuits

Nearly 900 pages and over
60 chapters. Puts the epics
to shame! Everything from
crystal sets to computer
circuits. If you want it — it’s
in here! Cat B-1780

‘20

Here's the book for any
serious environmentalists!
286 pages of circuits and
designs, building
instructions and even
component part numbers
for alternative electronic
projects. Control devices
for wind and solar power
systems — even an electric

casi77s 824%
National Logic
Data 14

Everything you ever wanted
to know about National
conductors but didn't know
who to ask. A valuable
reference source for any

library. $34 95

Cat B-4016

Mail Order Super Special

Ring or write (but you'd best

ring — these won't last)!
Quality Tasco 10 x 50 wide
angle binoculars complete

with carry case and strap at

an unbelievable price.
Cat Y-1115

SAVE $50!!

Now Only $99

Quality Needle
Nose

The best in quality tools
with these Mini Needle
Nose Pliers. Stainless steel
construction with tiny 1mm
non serrated tip for that fine
work. Fantastic value!

Cat T-3570 $g75

E-Z Cable
Checker

Every roadie, every band
should have one! Anyone
who's involved in audio will
find this the ultimate time.
saver. Simply plug your cable
in (and there's a socket for
every standard type) anda
series of LEDs tells you if it's

OK. $ 7 9%

Cat Q-1532

MAIL ORDER
ONLY!!!

24 piece Socket
Saver!

Save time and money with
this 24 piece socket set.
Complete with 9 long
sockets and 9 standard hex
sockets from 3/16” to %2". 4"
drive ratchet, two extension
bars, universal joint and

much more! NOW ONLY

Cat T-4837 $9995

Save $10

Auto Ranging 3.5
Digit

The compact Multimeter
with memory, two selectable
current ranges, auto ranging
for voltage and resistance,
visual overrange indicator
and everything a good
workbench
needs! 569
Cat Q-1515

S OMITH
ELECTRONICS

PTY LTD

Computer Saver

The Jabel line filter eliminates
spikes and other garbage
from the mains supply. Give
your computer a clean line of
supply —and now you'll $ave
$10 off our normal price!

An easy change
The RS232 Breakout Box is
ideal for modems and other
serial applications. DB25
male to female with pin 1
permanently wired — all the
others are open and supplied

with wire links.
vr

Cat X-3568

Permanent
Connections

The RS232 Jumper Box is
the DB25 connector made
for permanent connections.
All 25 pins are open with
wire links supplied ready
for soldering. Cat X-3569

$4 75

Access

Now you can have Videotext
access without having to own
a computer! The VDX 1000
Videotext Decoder connects
to your phone line and the
Videotext computer bank.
Once you become a
registered user you'll have
access to hundreds of pages

eatxer00”” SIOY
Antistatic
Computer
Cleaner

Designed to keep your your
valuable computer, screen,
etc. looking like new.
Cleans and deodorises in

one action! 95
Cat X-3562 3

Computer
Vacuum
Cleaner

A great idea for removing
grit and dust from
keyboards and circuit
boards. The Mini Vacuum
Cleaner is battery
operated and comes with
interchangeable heads
for all those hard to get at

places! 5. 4 9%

Cat C-7525
Beat Corrosion
EB Cortec’ wioevce

OM HOOD CORTES

Sealed Air Corporation

With Cortec 101 you need
never worry about

corrosion again! Simply
slip Cortec into your
electronic device and an
invisible vapour protects
it against corrosion for up
to three years. Ideal for
marine use. Cat D-1300

$625

Disks

in reliability!
5%" (13cm) format

Cat X-3510

Cat X-3512

Cat X-3514

(Box of 10)

Cat X-3516

5%" (13cm) Format

Cat X-3534

3%" (9cm) Format

Cat X-3533

Famous Xidex

From the world’s leading disk manufacturer Xidex.
Premium quality soft sectored diskettes for the ultimate

Single sided/double density (40 track) $450 ea
Single sided/double density (Box of 10) SAA box

Double sided/double density (Box of 10) 849% box

Double sided/high energy, 80 track

For AT machines with high capacity drives (1.2Mb)

Diskette Files

Top quality diskette files to protect those valuable disks.
Constructed of durable plastic with see-thru lids.

30 disk storage, with 3 fixed dividers and 5 movable

dividers/labels. $4 5%» Cat X-3528
50 disk storage. Lockable with 9 movable dividers. Cat

x-3531 WAS $23.50 NOW $2250

100 disk storage. Lockable with 9 movable dividers.

GAVE OVER $7 ONLY 529%

40 disk storage. Lockable with 4 movable dividers.

599

82 gs

Speech Saver

Save $50 on Votalker Speech Synthesiser! Voltalker board
slips into any PC compatible slot and converts written
English into speech with amazing clarity. Operates fromDOS
level or from word processor. Now talking to your machine

isn't so silly after all! Cat X-3572

SAVE $50 ONLY

$50 off Colour
Graphics Adaptor

Slots straight into your Multitech for improved games
playing capabilities! Who said computers are all work and

no play? Cat X-8140

WAS $249 NO

w°499

Mono Graphics Adaptor

The Hercules-compatible card for software requiring MGA
standard. Also includes a second parallel port and a $50

saving!! Cat X-8141

Now Only °249

Enhanced Graphics—
Lower price!

The most versatile all rounder you can get — PLUS you'll
save $50. The Enhanced Graphic Adaptor gives you switch
selectable MGA, CGA or EGA format. Perfect for desktop

publishing or highly graphics oriented software! §
Cat X-8142

Serial Data
Cable

2.35 metre serial cable (yes,
we're serial about this) with
male and female DB25
adaptors at either end (we
found it better to put them
on the ends). For computer/
computer connections,

modems, etc. $
Cat X-3564

Male Gender
Bender

You guessed it! It's just like
the one next door but this
one has a strong macho
image. Turns

her into him. $4 5s
Cat X-3565

Parallel Printer
Cable

Standard Centronics type
printer cable with 36 pin
Centronics plug on one end
and 25 pin D socket on
other. 1.7m long!

Cat X-8614 $3. 45

Female Gender
Bender

Adapts male serial cables
without re-soldering or
reconnecting. Simply plug in
twin female DB25 sockets
with all pins

wired.” $4 5»
Cat X-3566

Budget Swivel
Base

Quality constructed Monitor
Swivel Base for your
computer Screen (or your
telly). It's easier to twist the
screen than it is your neck!

Cat X-1190 $9495

Deluxe Swivel
Base

If you're constantly having to
adjust the monitor — so
others can see the screen,
etc — then this is the one for
you! Has knurled knob for
locking and freeing screen.

Cat X-1191 $ gs0

Gas-Lift Monitor
Arm

Allows you to move the
monitor into almost any
position with the little to no
effort. The computer cables
are hidden away in the arm

so it looks neat too! Cat X-1192

5345

Just a Shade of
Difference!

Great value monitors in
the two most sought after
colours — Green or Amber.

Amber Cat X-1224
Green Cat X-1223

‘249

$699 Get your
computer

on line!
Dataphone

1200

With pushbutton 12
memory phone 300/300,
600/75 and 1200/75 modes.
Plus auto answer/answer/
originate! Comes complete
with RS232 serial interface,
240V supply cable and
phone plug. Cat X-3300

$349

Dataphone
300

For the budget conscious
and now with a huge $30
saving! 300 Baud full duplex
modem with pushbutton
phone. Simply plug it in for
instant communication.

cat x-3301 Save $30

Now £469

Dataphone
4200/Smart

We don't call it Smart for
nothing! State-of-the-art
data transfer is made easier
and quicker than ever
before. Hayes-compatible
offering auto selectable
300/300, 1200/75 baud
transmission. Comes ready
to plug in! Cat X-3302

All DSE Modems

are Telecom $499

Approved

e NICAD SAVINGS ¢ NICAD SAVINGS e

GET UP TO 400 CHARGES OUT
OF OUR HEAVY DUTY NICADS.

Ideal for all your toys, radios...

Why buy Nicads? ; Battery Packs

ou should expect at least 400 charges from a NiCad

battery. If looked after, this can easily be doubled. Taking AA Pe ae oo hia

worst case, each charge for a "AA" cell costs about 1c Pyar

(electricity Costs are negligible). Compare this to 400 dry 2xC 1: 2Ah $-3152 $1 5.95

batteries at about 60c each. . . the savings are enormous! : xD -3154 $16.50

« h 4x AA TAK noo 83180 — S-3160 «$19.95
ut there’s more! 2xC—sS 200A ——Cié‘S‘-31162 = $224.95

A NiCad cell holds its voltage virtually constant over 90% of 2xD 4.0AN_ S38 164 $27.95

the discharge cycle. A dry cell starts dropping voltage

immediately. You don’t get the same "drop off’ ina NiCad Extra Heavy Duty NiGads

as a dry cell. Therefore motors continue to run at the correct
speed, lamps glow at the right brightness, and so on — ver Type Cat No. Price
cee to complete discharae, . we 20h S-3311 14.50
AA _600mAh $-3312 sae
q D 4.0Ah S$-3310 14.50
And even more: . Sub C Fast Charge $-3324 $6.50

The internal resistance of a NiCad Cell is much lower than a
dry cell. (less than 0.05 ohms Vs 0.4 to 0.8 ohms) Therefore
devices which require high currents (e.g. photoflashes, high
torque motors, etc) are much better off with NiCad cells than
dry cells.

Still not convinced?

You can get much higher continuous current ratings in a
NiCad cell than a dry cell. While not rated the same way, a
dry cell discharged at 90mA is considered “flat” (1.1V) after
approx. 2.5 hours. A NiCad cell lasts almost 5.5 hours
under the same conditions. Even under non-continuous
discharge conditions, the NiCad cell wins hands down:
because the NiCad can be re-charged between uses!

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SN ‘, Cat M-9518

Lh LW? on, e
P

ALL YOUR RECEPTION PROBLEMS
SOLVED... AT DICK SMITH ELECTRONICS

THE MAST

If reception’s not the best, get your antenna up
above the noise, up above the obstructions!
This 9 metre 3-section telescopic mast will do it:
and it comes complete with all mounting
hardware. Accepts virtually all TV antennas.

Cat L-4520 $4 4 0

THE GUY WIRE

Ultra-strong plated steel guy wire to hold mast
up against mother nature: breaking strain is
greater than 10 tonnes. 180 metre roll: just right

for mast installation. Cat L-4564 $ A A

THE TURNBUCKLES

There’s no safer way of making fast the guys.
Turnbuckles allow fine adjustment of tension to
ensure mast is vertical, too. Heavily plated,
8mm size (94mm long). Cat L-4544 $4 65

THE WIRE CLAMPS

Gives the safest, strongest method of tying off
guy wires. Minimum strain, no kinks to becom
weak points. Use wherever guy wire ends.

Cat L-4522 7 0 ¢

THE THIMBLES

Makes guy wires follow wide radius wherever

they change direction (eg at top and pottom) to

avoid creating weak points. A must fpr safety —

and they're so cheap! Cat L-4530 f 0 ¢
e

THE DYNABOLT

Use for anchoring the guy wjfes into cgncrete,
etc. Two styles to choose frgm — onée/standard
hex nut type and the other ef for taking
turnbuckles or guy wires.
10mm Hex Head:Cat L-459. Pack gf 3 $995

yourself. Our specially written guide saws
how: what to do, how to do it, everythings Cat B-6010
And the price? Just 50¢! (Or buy any TV
antenna or mast and we'll give you a copy!)

THE ANTENNA

No, we haven't shown the antenna — because
the type is up to you! VHF, UHF Band 4, UHF
Band 5, Combined VHF/UHF, FM Radio,
metropolitan, fringe... there’s a huge range to
suit from — but one will be just right for you.
See next page for just some of our value-
packed antennas.

THE MASTHEAD AMP

If you're scratching for that last bit of signal
(because of area, ghosting, etc) a masthead
amp often works wonders. Amplifies signal right
at antenna — and it is especially designed to
minimise CB interference, too. 24dB
gain,includes power supply and amplifier unit.

Cat L-4200. $75
THE LEAD-IN

Choosing the right lead-in makes a world of
difference. In strong signal areas, 300 ohm
ribbon is usually fine, but for best results you
need our low-loss 5C2V low-loss air dielectric
coax. Black coloured to minimise UV damage.

Cat W-2082
75°

THE ROTATOR

Trying for a number of stations? If you're on the
fringe, a rotator will allow best aiming. Simply
clamps to mast and antenna, needs only three-
wire control cable. Includes rotator and inside

control box. Cat D-5005
$229
THE SPLITTER

Wan\\to run more than one TV? You need a
ittar. Choose from two or four way, coax or
lead-in type. For example, took at the low

DSE — working in New Zealand for Hobbyists — Save!

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Save $24 on our

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commercial unit you'd price? It’s the bare-
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more. Features 2 instant build a complete
and 6 delay sectors, system for the home
security key, inbuilt office around it! And
battery backup and
more!! Cat K-3424

value. Cat K-3254

Buzzer

The hobbyist's workmate!
Amazing value Multimeter
with Audible Continuity
Tester. Has battery checker,
10A DC range and high
sensitivity (20K ohms),
mirrored scale and that

famous DSE LOW price! SNZDQ95

Cat Q-1022

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Yes, the incredible DSE
Workstation with adjustable
temperature control is now

the best value yet! Puts an

end to all those soldering

hassles for a truly
professional finish. Comes
with lightweight iron holder,
sponge and comprehensive
instruction and service
manual. Cat T-2000

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— and itevenfitsin your A meee any tool kit.

pocket! Works just like a = Desolders cleanly and

cigarette lighter — uses _ professionally in seconds.
refillable butane. Provides Huge 30 watt rating, fully $NZQ95

an amazing 60 minutes
heat at an equivalent of Ideal for workshop,
10 to 60 watts. home, technicians...
Detachable cap features = anywhere, anytime!
a built-in ignition system. Cat T-1340

Cat T-1370

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self contained 240 volt.

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fantastic 8 Sector Home get a quality 4 Sector Easy to put together — small bands, etc! Use Save on our Beat
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ane} ; have it flash to the beat
individual inputs. More of the music. Fantastic
nothing gives you better everything that's needed featuresthanthelocal — for photography — kit
and features even more Movie house! Cat K-3036 ¢omes complete and
ready to assemble.

Cat K-3153 Noise Reduction
SNZ26995 System is the ideal,

SNZ6995

No.1 For Kits -And Getting Better! s:2:."

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and at this price, it's i
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or unit ata hobbyist price. aNd impedance on
Kit comes with

than you need.
Cat K-3437

N249

SNZQQ

Budget Mini Meter

Here's one Multimeter no
workshop can afford to be without.
For well under $20 you get an 11
range, 2000 ohm/volt pocket sized
tester. Ideal for general work and
it's rugged and reliable!

Cat Q-1010

SNZ4 4°

‘4 off Soldering
fron The mini vice from Arlec
Save nearly $10! Our attaches to any table, bench
super value, high quality etc and leaves your hands
‘Antex’ brand iron will get free for the job! 50mm jaws
the job done — with 25 open to about 60mm for the
watts it's hot when you really big jobs. Ideal for
need it. Reliability with cutting, filling and test
stainless steel barrel and applications. Cat T-4748
copper tip. Cat T-1300

—— sNZ4Q95 SNZ4 4

A S Great for a thousand and one
aed projects! The DSE 2155

‘2 price Solder transformer with 15, 17.5, 20,

50mm Roll 200g 1.25mm_ 24, 27.5 and 30 volt tappings

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See
NOW CS) easy connection. Cat M-6672

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& "24

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2 Circuit Saver

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There’s real savings on our
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coloured pens and eraser in

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The only thing smaller
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price! It performs better
than a lot of 75mm jobs. 8
ohm impedance make it
suitable for many
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Electronic Marvel
Professional quality at a hobbyists
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read peak-to-peak and RMS — but
this one can. You can even adjust the
pointer to zero for nulling! With a
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swapping. Cat Q-1143 SNZQ,995

Get a grip on your work

45-30 volt M/Tap Transformer

J

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about anything — but
they say these things
help you feel better.
. Cat K-3333

VCR Simulated
Stereo

The DSE Dynamic

inexpensive way to to
reduce hiss AND add
simulated stereo to

your mono VCR! Easy
to build and set up.

Economy Wire
Stripper

w We've stripped over

: 4 :
a 25% off the price of

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of time on those
projects with this
versatile tool. With
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$NZ 55

Quality Side Cutting
Pliers — $7 off
normal price!
Insulated handles
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construction make
them ideal for
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Cat T-3270

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BO inh LO Yeas tod..

“Electronics Australia’’ is one of the longest running technical publications in the
world. We started as “Wireless Weekly” in August 1922 and became ‘Radio and
Hobbies in Australia” in April 1939. The title was changed to ‘‘Radio, Television
and Hobbies” in February 1955 and finally, to “Electronics Australia” in April
1965. Below we feature some items from past issues.

June 1937

625-Foot Mast: The General Electric
Company has announced that it will
erect an ultra-modern 625-foot vertical
antenna for its station, WGY in Sche-
nectady, and by doing so will increase
the effective signal strength of this
50,000 watt transmitter at least three
times. The plans to ‘give this pioneer
broadcasting station one of the tallest
antenna systems in the country have

JUNE CROSSWORD

SSSR RS ses
tat Aaa

been approved by the Federal Com-
munications Commission and work will
start at once.

Radio equipment for the Army: Wireless
is playing an increasingly important part
today in the army and is especially suit-
able for the training of troops. Special
apparatus has been developed for the
purpose, the requirements of this type
of appliance being durability and mobil-
ity. Transmitters and receiving sets are
mounted on motor vehicles so that they
can be transported readily from place to
place. They are designed to transmit
both speech and Morse. Amplifying fa-
cilities are also required so that a num-
ber of men can hear instructional com-
ment.

[CTHJE[B]Y[SJHIE]V i BIRIAIGIG]

HbHARH ©

ACROSS 11. Useful place for a 17. Type of diode. (6) Baan OS a ea

magnetic plug. (4) 20. Symbol used for XTEINIOIN IMF] IVIE!

1. Device triggered by 12. Type of wing used on wavelength. (6) (EMAMES) IBESBR

microwaves. (5,8) F/A18. (5) 22. Accurate measuring RIAL egos S|

8. Phenomenon affecting radio 13. Applied to a pinball instrument. (7) IDMEV LAITIEIL ME CIOIP/PIEIR|
reception. (7) machine. (4) 26. Hyperbolic function. (4) a © [PNR]

10. Said of a number witha 16. Effect of troposphere on 27. What EFTS can do to your Os aaa

radix of three. (7) radio beams. (7) account. (5) DEGRADE
28. Sixth letter of Greek IS] Vv Baan

alphabet. (4)

indicator circuit. (7)

adaptor. (6,7)
DOWN

(6)
2. Said of non-static
characteristic. (7)

fibres. (4)

31. Part of automotive traffic

32. Type of potentiometer. (7)
33. Male-to-female D-type

1. Substance used to prevent
etching in PCB manufacture.

3. Twisted cable of natural

4. Elevate retracted antenna.
6

5. Doughnut-shaped rings. (4)

6. Adjust relative position. (7)
7. Used in CB radios. (8)

June 1962

Flight to the Moon: President Kennedy
has set a manned landing on the Moon
as a United States goal. The known and
unknown problems of such a mission
make Columbus’ search for a new route
to the East, by comparison, about as
risky as betting that the postman will
come.

No need to refuel: Throw-away cigarette
lighters costing the equivalent of about
5/6 each are now on sale in France.

Cylindrical in shape and about
3-inches long, they are of the gas-filled
type and are ignited by means of the
usual milled wheel and flint. The wheel
extinguishes the flame when it is pushed
slightly forward by the thumb.

A red line on the transparent base of
the lighter acts as a guide to the level of
the gas and the user can readily see
whether it is time to buy another. The
lighters will last an average smoker
three months. ;

SOLUTION FOR MAY

9. Inventor of maser and
proponent of the laser. (6)
14. Etude. (5)

15. Possible results of severe
electric shock. (5)

18. Electronic device with
unknown contents. (5,3)

19. Sequential connection of
components. (6)

21. Pattern substrate etching.

(7)

23. End of the day. (7)

24. Unit of phase difference.
(6)

25. Possible indication of a
siren. (6)

29. Conductors at high (4)
frequencies exhibit a — effect.
30. Type style for a printer. (4)

ELECTRONICS Australia, June 1987 83

Monitor signal levels with this

Low-cost
stereo VU meter

Here we present a general purpose stereo
VU meter which features easy construction
and installation. It’s sensitivity can be
adjusted down to 3mV so it can be driven by
any audio signal source, including a low
impedance dynamic microphone.

by BRANCO JUSTIC

This versatile stereo VU meter may
be added to the Mini Mixer described in
our May 1987 issue, or to any other
item of audio equipment. The unit is
based on a single IC and, in addition to
functioning as a VU meter, could also
be used as a simple stereo preamplifier.
It is based on a low cost meter move-
ment and all the parts are mounted on a
small printed circuit board.

Mechanical meters

The use of mechanical meter move-
ments in consumer electronic equipment
is rapidly diminishing. The reason for
this becomes very apparent when their
prices are compared to the various elec-
tronic displays currently available. Me-
chanical meter movements are expen-
sive!

But while LED and LCD displays

SEE TEXT

STEREO VU METER
1/MS/-

perform better in most applications,
many people still prefer mechanical
meter movements for use as VU
meters. The current availability of some
very inexpensive stereo meter move-
ments on the disposal market has
prompted the presentation of this proj-
ect:

How it works

We will discuss the operation of the
left channel only; the right channel cir-
cuitry is identical.

The input signal is first applied to
variable attenuator VR1 and then AC
coupled via C1 and R1 to pin 6 of ICla.
VRI1 functions as a sensitivity control
and allows the sensitivity of the VU
meter to be adjusted to suit different
levels of input voltage (from 3mV to
several volts).

The required gain is produced by cas-
caded op amp stages ICla and IClb.

O+6-12V OR
6-12VRMS
(E.G. FROM MIXER)

The left and right channel inputs are amplified by the op amp stages, rectified and applied to the meter movements.

84 ELECTRONICS Australia, June 1987

The prototype was housed in a small plastic case. Backlighting for the meter scales is pro-
vided by two small 6V lamps mounted on the PCB.

These produce voltage gains of approxi-
mately -39 and -7 respectively, giving
an overall gain of 273. The amplified
signal at the output of IC1b is rectified
by diodes D1 and D2 and the resultant
fluctuating DC current applied to the
meter movement (M1).

The input supply voltage is applied
via diode D3 to filter capacitor C4 and
the operational amplifier IC. D3 serves
to isolate the op amp circuitry from the

two lamps which draw relatively high
current (approx. 200mA).

Construction

All the components, including the
meter movement, are assembled onto a
PCB coded 87vuS (96 x 53mm).

Start construction by assembling all
the parts onto the PCB as shown in
Fig.2. Watch the orientation of the inte-
grated circuit, electrolytic capacitors and

This view shows the assembled PCB, prior to installation of the meter.

MEicroGram

COMPUTERS

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INTERFACE CARD

Designed for IBM/PC/XT/AT and
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More than just a GPIB Controller.
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GPIB Bus analyser with four
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SELECTRONIC

ELECTRONICS Australia, June 1987 85

q

ARRAY, ty ;

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the diodes, and leave the meter move-
ment till last.

Note that an insulated wire link
(shown dotted) is run on the copper
side of the PCB to connect the two
6.3V 200mA lamps in series. This ar-
rangement consumes approximately
200mA from a 12V supply. Alternative-
ly, the lamps could be wired in parallel
in which case they would require 6V at
400mA.

If the required voltages or currents
are not available, the two lamps could
be omitted. Alternatively, two high in-
tensity LEDs with a suitable series resis-
tor could be used to backlight the VU
meter.

The prototype was built into a small
plastic zippy case measuring 116 x 34 x
65mm (W x D x H). For those readers
who wish to follow suit, it will be neces-
sary to cut a hole measuring 46 x 36mm
in the base of the case to provide clear-
ance for the meter. The meter-cum-
PCB assembly is then secured by means
of two 4mm-long screws (see photo).

PARTS LIST

1 PCB, code 87vu5, 96 x 538mm
1 stereo VU meter movement

2 6V 200mA lamps

2 5mm 100k? trimpots

Semiconductors

1 CA3401, LM3900 quad op
amp

1 1N4001 silicon diode :
4 1N4148 silicon diodes Here’s what the fully assembled unit looks like with the meter in position. Note the use of
Capacitors shielded cable for the left and right channel signal inputs.

4 0.1F monolythics
4 4.7uF 16V electrolytics
1 100uF 16V electrolytics

Resistors (0.25W 5%)

2 x 8.2MQ, 2 x 4.7MQ, 2 x
3.9MQ, 2 x 2.2MQ, 2 x 330kQ, 2
x 100kQ, 2 x 10kO

4.70F py 4.7pF°100UF @4.7uF pq) 4.7yF
«-1{-o
we

Where to buy the parts: a kit of
parts for this project is available
for $17.95 from Oatley
Electronics, 5 Lansdowne Pde
(PO Box 89), Oatley, NSW 2223.
Phone: (02) 579 4985. Price

A oR LEFT LN

includes pack and post; add 6-12VRMS INPUTS

$2.60 for the plastic case.

Note: copyright of the PC
artwork for this project is owned Follow this layout diagram carefully when assembling the PCB and make sure that you
by Oatley Electronics. install the IC the right way round. The unit can be powered from any 6-12V AC or DC
supply.

ELECTRONICS Australia, June 1987 87

The ins and outs

of Local Area
Networks

What they are & what they do

As the use of computers in business has become more
widespread, a particular bottleneck has developed and
become more critical: the inability of computers to
communicate with each other easily. This has led to the
development of the Local Area Network (LAN). In this first of
a series of articles we shall introduce the concept of a LAN

and talk about the IBM token-ring.

by DAVID CARTWRIGHT & GREG PEAKE

Texas Instruments Australia

In simple terms, a Local Area Net-
work (LAN) provides a standard
method of connecting various types of
electronic equipment in a small area
such as an office or a factory. The elec-
tronic equipment today is most likely to
be a personal computer but it could ex-
tend in the future to a whole range of
equipment such as facsimile and photo-
copier machines to process controllers
in a factory.

When connected in a LAN, each de-
vice can operate independently but can
communicate with any other on that

APPLICATION
PRESENTATION

TRANSPORT
802.1 NETWORK CONTROL

NETWORK
802.2 LLC

SEs
OSt MODEL IEEE MODEL
(a) (b)

This diagram shows the seven layers of the
open systems interconnection (OSE) model.

88 ELECTRONICS Australia, June 1987

network by relaying messages, files,
documents, or raw data.

Typically, LANs are privately in-
stalled and maintained, hence they are
classified as “Private Data Networks”.
Despite the fact that they are private
data networks, there has been a grow-
ing trend in the past few years towards
international standards. The pressures
for setting standards include lower costs
that result from volume semiconductor
manufacture, as well as access to a wide
range of software supporting the major
LAN standards.

Let’s now look at the major LAN
standards as defined by the US Institute
of Electrical and Electronics Engineers.
Later, we will examine in more detail
the IBM Token-Ring LAN as defined
by IEEE (802.5).

The open systems
interconnection model

When discussing networks, whether
they be local area networks or wide
area networks (eg, the public telephone
system), the most popular is the open
systems internconnection (OSI) model
developed by the International Stand-
ards Organisation. This seven-layered
model (see Fig.1(a)) is designed to stan-

dardise data communications between
networking equipment.

By comparison, a conventional per-
sonal computer has three layers of soft-
ware and hardware. The first layer is
for applications programs which may be
anything from wordprocessors to
spreadsheets. The second software layer
is the disk operating system (DOS)
while the third layer is BIOS or Basic
Input/Output System which is the oper-
ating system of the hardware and, in the
case of computers like the IBM PC, is
accommodated mainly in a read only
memory (ROM).

Let’s briefly examine the functions
performed by each of the seven layers
of the OSI model.

Application layer

The application layer is the same as
for the conventional PC described
above. It allows a user to perform func-
tions such as data entry, file transfer
and electronic mail. At the application
level, a user might use a word pro-
cessor, a spreadsheet such as Lotus 1-2-
3, or a database such as dBase II].

For example, imagine that in an ac-
counting department there are ten users
of disk-less personal computers (PCs).
These disk-less PCs are connected via a
LAN to a larger PC which has a 40
megabyte hard disk.

Due to the ability of the network,
users of the disk-less PCs are able to
store and retrieve their data or pro-
grams via the hard disk of the larger
PC. These transactions can be totally
transparent to the user to the extent
that, as far as he or she is concerned,
the data is stored in their own PC.

For this type of transparency, the
software and hardware of the lower
layers of the OSI model have to effi-

ciently move the data from the disk-less
PC to the PC with the hard disk. This
communication path should be fast and
error-free.

There is however no reason why one
has to be restricted to a large PC for
data and program storage. For example,
a larger LAN could involve an office of
200 users using stand-alone or disk-less
PCs and all served by a mainframe com-
puter.

The advantage of a LAN in this situa-
tion is that instead of each PC having its
own hard disk and data base, accessible
via that machine alone, users can now
share a larger common data base. This
resource sharing capability is equivalent
to that offered by a multi-user mini-
computer or mainframe computing sys-
tem. However, for the example of the
accounting department, the LAN sys-
tem cost can be far lower than that of a
mini-computer.

Presentation &
Session Layers

Let’s now look briefly at the lower
layers of the OSI model. The communi-
cation path can be defined in terms of
different elements supported by each of
the layers.

In the Presentation layer, data is
transferred into a format suitable for
the Session layer. For example, it might
be necessary to compress or expand the
data, perform encryption or decryption,
or generally convert the data format to
one recognised by the succeeding layers.

The Session layer then manages and
synchronises the conversations between
the application layers while the Trans-
port layer multiplexes and segments the
data for efficient transmission. The
Transport layer also ensures that data is
sent and arrives correctly at the destina-
tion.

Network, data
and physical layers

Routing of communications through
the network, particularly applicable
when the LAN is connected to another
LAN or a Wide Area Network, is pro-
vided by the Network layer. Some error
correction is also performed within this
layer.

The Data Link layer provides the
transmission format of data and control
on the network for the information to
be transmitted over the physical link.

Finally, the Physical layer provides
the mechanical and electrical aspects of
the network.

An example of the flow of informa-
tion between two users is illustrated in
Fig.2.

IBM TOKEN-RING NETWORK

STAR-WIRED
TOKEN PASSING RING

Inserted i

into ring ears,

Wiring
Inserted

into ring

Deinserted
from ring

Logical ring — physical star
Compatible with IEEE 802.5
standard(4 Mbps)

Information transmitted via “Token”
Strengths

—Collision free

—Good under heavy loads
—Ease of reconfiguration

—Uses twisted pair (telephone or
shielded) or fiber optic cabling

Fig.6: the IBM token-ring network depends on the transmission of a unique bit pattern
before each terminal or station is given access.

ENGINEERING

CAD
WS

CAD
WS

CAD
WS

PC: Personal Computer
IC: Industrial Computer
CAD WS: Engineering Workstation

While local area networks often apply to just a few users they can embrace very large

numbers of users and applications.

ATTACHING

LAYER: PRODUCT

APPLICATION
PRESENTATION
SESSION
TRANSPORT
NETWORK
DATA LINK

PHYSICAL

ATTACHING
PRODUCT

PHYSICAL MEDIA OF OSI

Data has to be passed up and down all the layers of the network to be transmitted be-

tween users.

ELECTRONICS Australia, June 1987

89

Design in
’snew

The new IBM® Token-Ring Network
promises to become the industry stan-
dard. And if you are wondering about
the: best and quickest way to tie your
product into this new 4-Mb/sec LAN,
here's your solution: The TMS380 chip
set from Texas Instruments.

TI's TMS380 is the only commercial
chip set tested — and system-verified —
by IBM. It’s the silicon standard for this
new high-speed office-system LAN.

And for a sure, fast entry into this
exciting new market, you can begin with

TI's TMS380 Design-in Accelerator Kit.
Q. What kinds of products can
communicate through the
new LAN?
A. With the TMS380 chip set,
almost any.
TI's new TMS380 chip set was developed
jointly with IBM. Its general-purpose
f system interface allows many kinds of
TMS380 equipment from various manufacturers to
Adapter Chipset communicate through the IBM Token-
User’s Guide Ae Pnataae Ring Network. And since this is an open
is, network, any product in which you use
the TMS380 can communicate with any
. other, when common languages are used.
oe Q. Is expensive cabling required?
A. No.
Your customers have the option of using
telephone twisted pair or shielded twisted
pair. And the point-to-point topology of
the token ring makes it ideal for fiber
optics, since the taps that are necessary
with bus topologies are not required.

Q. Where does TI’s TMS380
chip set fit in?
A. It’s the heart of your LAN
adapter card or subsystem.
The TMS380 chip set is.a complete
solution for the physical interface and
media-access control. Its integrated
LAN-adapter architecture provides for
efficient, transparent handling of the
IEEE 802.5 protocols. TI's TMS380 in
your product will give your customers free-
dom to choose the cabling system that
best suits their needs. And the flexibility
to interface with any of the popular logical-
link-control and higher-layer protocols.

Everything you need to begin designing your
own IBM Token-Ring Network LAN adapter
is included in your TI Design-in Accelerator
Kit: Three TMS380 chip sets, comprehensive
literature, and debug software.

*Registered trademark of International Business Machines Corp

IBM compatibility with
token-ring-LA N chip set.

TEXAS INSTRUMENTS
FIELD SALES OFFICES

TMS380 LAN ADAPTER CHIP SET

oie
COMMUNICATIONS
oie
Melbourne: (03) 267-4677
Sydney: (02) 887-1122
LAN ADAPTER BUS .

TRANSMIT

TEXAS INSTRUMENTS
DISTRIBUTORS _

ADELAIDE:
EC & E:(08) 232-0001
VSI: (08) 267-4848
BRISBANE:

Five TMS380 chips form the heart of your LAN adapter. The TMS38030.-automatically
manages the interface between system memory and the adapter. The TMS38010 processes and
buffers data. The TMS38020 contains RAS and LAN-management software and handles
data in accordance with [EEE 802.5 protocols. And the TMS38051 and TMS38052 monitor
cabling integrity, control network insertion, and perform clocking and signal conditioning.

Rifa: (07) 832-3700
VSI: (07) 52-5022.

Q. What about network
management?
A. Every service your system
needs is built in.
TI's new TMS380 chip set includes “self-
healing” features that ensure the re-
liability, availability, and serviceability
(RAS) of the network. And only the
TMS380 chip set has them.
Among these special features are fault
isolation of cable-system failures, error

reporting, self-test diagnostics, and LAN-

management services. So you're relieved

of the risk, time, and expense of develop-

ing custom hardware and software for

these essential functions.

Q. Can it grow with my needs
and my customers’?

A. Yes.

On-chip RAS and LAN-management

software make TI's TMS380 chip set

completely compatible with the IBM

Ring Network compatibility into your
products. It includes three chip sets, the
TMS380 User's Guide, and the Token Ring
Adapter Bring-Up Guide with debug soft-

i
TEXAS w
INSTRUMENTS

Creating useful products
and services for you.

6 Talavera Rd.,
North Ryde 2113

MELBOURNE:
Rifa: (03) 480-1211 |
VSI: (03) 543-6445

PERTH: |
VSI: — (09) 328-8499

SYDNEY:
Rifa: (02) 858-5966.
VSI: (02) 439- 8622.

To: Texas Instruments Australia

L] Please rush me a TMS380 Data Package.

Token-Ring LAN and give it a stable C1 Place my name on the TMS380 Mail List.
foundation to meet the need for future
network expansion. As higher perfor-

|
|
|
|
|
|
|
|
I
|
|
|
mance standards develop, the TMS380 |
|
|
|
|
|
|
|
|
|
|
|
|
|

chip set will accommodate them. Company fe: ena (oases Tare ts ave over lave terete rw eis sara eiara tole Vere au bie}ai slater oteraveiels
Q. What’s this about an INI 6 2 5ncs:ks ans xsu negra ties. overepamaan eee RCO Ta rune
Accelerator Kit? Re EGS) “arinssits sacciconmn RABE tena aces BERN Catena eee
A. It’s your head start to IBM
token-ring compatibility PAI Soi eo dak weeds’ Subueby usscsccscasss State ...........
TI's Design-in Accelerator Kit will give you
ahead Bt carci =i na Postcode ....... Ph: ( ). srosaR clerend seaeene et aoe

IEEE LAN standards

Currently there are three major
LAN standards defined by the IEEE,
each of which have different topologies
and accessing procedures. These are as
follows:

@ IEEE 802.3 — A bus topology imple-
menting Carrier Sense Multiple Access
with Collision Detection (CSMA/CD).

e JEEE 802.4 — Bus topology using a
token-passing access method.

e IEEE 802.5 — Star-wired ring topol-
ogy using a token-passing access meth-
od.

Fig.1(b) illustrates how these three
LAN standards compare with the OSI
model of Fig.1(a).

As will be seen later, these standards
only relate to the Physical layer and the
Medium Access Control (MAC) which
is used in the Data Link layer. The
MAC defines the method of access used
by the particular LAN standard. The
three networks all use the IEEE 802.2
standard for the Logical Link Control
(LLC) level of the Data link layer.

And while it is not obvious from Fig.
3, it is possible to run the same upper
layer protocol software over the three
different LAN topologies. We will look
at an example of this in the next article.

STARTING
DELIMITER
1 BYTE

ACCESS ENDING
CONTROL DELIMITER
1 BYTE 1 BYTE

FREE TOKEN FORMAT

STARTING | ACCESS FRAME |DESTINATION| SOURCE BRURTON
DELIMITER | CONTROL | CONTROL | ADDRESS | ADDRESS |'NFORMAT
1 BYTE 1 BYTE 1 BYTE 6 BYTES 5 BYTES

FRAME FORMAT

Fig. 3

FRAME
CHECK
SEQUENCE
4 BYTES

FRAMI
STATUS
1 BYTE

ENDING
DELIMITER
1 BYTE

Local area networks transmit and receive data in serial mode, in a frame format.

LAN terminology

Before proceeding to a discussion of
the major LAN standards, we will
briefly define a number of terms.

Bus: a network arrangement for the
transmission of data. Bus Conflict: see
Collision.

Carrier: an audio or radio signal which
can be modulated for the transmission
of data.

Collision: an attempt by one or more
stations in a LAN to send data at the
same time. In some systems, the detec-
tion of a collision causes all stations to
stop transmissions.

CSMA/CD: Carrier sense multiple ac-
cess with collision detection; a method
of regulating LAN transmissions to
avoid collisions.

DTE (Data Terminal Equipment): this

innovation + service = Total Commitment
Thyristors, Transistors, Diodes. Complete Power Range.

Stud, Transi or Discretely. We Can Turn You On.
Try Us.
SEMIKRON:P.O. Box 182, Springvale, 3171 (03) 561 3044

92 ELECTRONICS Australia, June 1987

term refers not just to computer termi-
nals but to parts of any distributed com-
puting system. This includes personal
computers, workstations, microproces-
sor-based photocopiers, point-of-sale
terminals, and even microprocessor-
based electricity consumption meters
which allow remote access via a
modem.

Frame: when digital information is
transmitted between DTEs the data is
arranged, by the data-link layer, into
packets called frames. Included in these
frames is information regarding address-
ing, bus control, and error detection.
An example of the frame formats used
in the Token-Ring LAN is given in
Fig.3.

Node: a connection or switching point in
a LAN.

Protocol: a set of rules ensuring that in-
formation exchanged within a network
can be received and interpreted cor-
rectly by both the transmitting DTE and
the receiving DTE.

Token: a unique bit pattern used to tell
stations in a LAN when they can trans-
mit data.

Topology: the arrangement of transmis-
sion paths ina LAN. The most common
are rings (where data is presented to
each station in turn), stars (where data
passes through a central node), and bus
(where data is presented to all stations).

IEEE 802.3: CSMA/CD
bus topology

Currently the most popular network
of this type is Ethernet which was a
joint development of Digital Equipment
Corporation (DEC), Intel and Xerox.
Ethernet has a theoretical maximum
speed of 10 megabits per second
(Mbps), although due to bus conflicts
actual performance is generally between
1 and 3 Mbps.

(For a further discussion on LAN
performances we recommend an article
by AT&T's Bell Labs researcher Bart
Stuck. His article, “Calculating the
Maximum Mean Data Rate in Local
Area Networks” appeared in the IEEE
publication “Computer”, May 1983 edi-

Ww
TEXAS
INSTRUMENTS

LOCAL AREA NETWORK
DEVELOPMENT SYSTEM

Includes: Texas Instruments Professional Computer

e TMS 380 LDK Design for token ring network e TND 380 TWC Test
-in Accelerator Kit e TMDS PCF LAN inter- wiring concentrator

with complete chip set face card with debug software

ENTRIES CLOSE 15th SEPTEMBER, 1987

HOW TO WIN Entries will be
judged on

Simply explain in less than 500 words why you de- —-Tginality and

serve to win this Local Area Network Development presentation.

System. Send your entry to
The Editor,

Entries should include details of at least one Electronics Australia,

PO Box 227,

LAN application for which the system will be used. waterioo 2017

The winner will be notified by mail and the result announced in the November 1987 issue of
Electronics Australia

tion. Most university libraries .hould
have a copy of this publication).

In a typical Ethernet network, all
DTE’s are connected to a single bus —
see Fig.4(a). The bus is accessed by
means of ‘“‘tapping’” circuitry which
monitors the bus status as well as ena-
bling data transfer to and from the bus.
The “tapping” circuitry or Medium Ac-
cess (MA) unit contains a transceiver
unit for data transfer to and from the
bus, and a Medium Access Control
(MAC) unit for frame handling and
error detection — see Fig.4(b).

Before transmitting a frame, the
MAC unit monitors the bus to deter-
mine if a carrier signal is present. If an-
other frame is already present on the
bus, the DTE (or DTEs) trying to send
a frame will defer transmission for a
certain time interval, after which it at-
tempts again. Once access is gained to
the bus, the frame is sent.

While sending a frame, the bus sig-
nals are constantly monitored for colli-
sion detection. A frame is not regarded
as fully despatched until a Frame Check
Sequence (FCS) has been transmitted.

However, because of propagation
delays within the network, collisions
from other transmitting DTEs can still
occur. When a collision is detected, a
“jam” signal is sent by the originating
DTE to reinforce the collision to all
other DTEs on the bus. After a short
randomly selected time interval, the

transmission of the original frame is at-
tempted again. In the event of continu-
ous collisions a limit is set for the maxi-
mum number of re-transmissions of a
single frame.

Any frame that is transmitted is re-
ceived by all MA units connected to the
bus, but not necessarily all DTEs.
When the MA unit receives a frame,
following clock synchronisation, the des-
tination address is checked to determine
if frame processing should continue. If
so, then error checks using the Frame
Check Sequence (FCS) and the frame
length indicator are made. If any of
these tests fail, the frame is discarded.
Assuming a valid frame, the frame is
stripped and the information field
passed to the DTE.

IEEE 802.4: Token-passing
bus topology

The MAP (Manufacturing Automated
Protocol) standard is the most popular
system using a token-passing bus topol-
ogy. The history of MAP revolves
around General Motors, who have
specified MAP for all their factory net-
working equipment, such as robots and
programmable controllers.

Under error-free conditions, the
token-passing bus is similar to the
token-ring network, except that the bus
method “broadcasts” (see Fig.5(a))
while the ring method is “sequential”.
With the token-passing method, the

TERMINATOR

INTEGRATED TAP
TRANSCEIVER UNIT

PREAMBLE

where PREAMBLE

DATA UNIT

WHERE

SD,FC , DA, SA

transmission of data onto the bus can
only be accomplished when a DTE is in
possession of the token. In passing the
token to the next DTE (successor), the
originating DTE listens to the bus to
see if the successor is active.

If active, the successor sends a valid
frame, which may be the token or an
information frame, to its successor (see
Fig.5(b)). If no frame is heard in a
specified time slot, the token is sent
again. When a frame sent by the succes-
sor is corrupted, then the token sent is
assumed to have been corrupted and is
sent again. A lack of response from the
successor after a second token is sent
causes the network to reconfigure and a
new successor is established.

The token-passing bus has a priority
system similar to the token-ring
whereby a DTE with high priority
frames can send a specified number of
frames before frames with lower priority
can be sent. If there is still allocated
time available after all high priority
frames have been transmitted, lower
priority frames can be sent. The token
is then passed on to another DTE.

IEEE 802.5: Token-passing
ring topology

The most popular implementation of
the 802.5 token-passing ring topology is
that used by IBM (International Busi-
ness Machines Corporation). This net-
work is generally referred to as the IBM
Token-Ring Network. Research in a

(ii) OTE H NOT PART OF LOGICAL RING AND HENCE !S RECEIVE ONLY

ED

DATA UNIT FCs

pattern sent to set receiver's modem clock and level (1 or more outlets)
SD _ start delimiter (1 octet)

FC frame control {1 octet)

DA destination address (2 or 6 octets)

SA source address (2 or 6 octets)

information (0 or more octets) FCS

frame check sequence (4 octets)

ED end delimiter (1 octet)
The number of octets between SD and ED. exclusive shall be 8191 or fewer.
The abort sequence shall conform to the following format:

SD ED |

SO _ start delimiter (1 octet)

MAC UNIT
|
PROTOCOL CONTROL FIRMWARE
Ie ore

|
=~ COMMUNICATIONS

| SUBSYSTEM ED end delimiter (1 octet)

Within this section the following acronyms are used for the addresses of the station under
discussion., its successor and its predecessor in the logical ring:
TS this station's address
NS next station’s address
(b} PS previous station's address

Fig. 5

The Ethernet LAN uses taps which monitor the status of

Token-passing bus topology is similar to the token ring.
the network.

94 ELECTRONICS Australia, June 1987

ring LAN began at IBM’s Zurich Re-
search Laboratory in 1979.

In 1982 IBM and Texas Instruments
signed an agreement whereby Texas In-
struments would develop a_ chip-set
compatible with IBM’s token-ring LAN
standard. On October 15, 1985 IBM an-
nounced its token-ring LAN while on
the same day Texas Instruments an-
nounced availability of its TMS380 chip-
set which implements the IBM stand-

ard.

Since October 1985 IBM _ has an-
nounced a variety of token-ring LAN
products which enable LAN links to
DTE’s ranging from PCs to mainframes.
In addition to IBM, essentially all major
computer and LAN manufacturers are
committed to developing products for
the token-ring LAN. Clearly, the IBM
token-ring LAN looks set to become
the industry standard for office environ-

ment.

In the second of these articles we will
examine software for the network, es-
sentially layers three to seven of the

OSI model, while in the final article we

will study the bottom two layers. For
the moment, we will provide an over-
view of the topology and compare the

Token-Ring LAN with Ethernet and
MAP.

IBM token-ring topology

The token-ring network resembles a
star-wired ring (see Fig.6). Each DTE,
or “station” as they are generally called
in IBM literature, is connected via
switching relays to the ring.

The relays are located in a central
unit called a Wiring Concentrator to
which all DTE’s on the network are
connected . If a fault develops in the
Token-Ring LAN, either with a DTE or
the cable between a DTE and the Wir-
ing Concentrator, that DTE is automati-
cally disconnected with the rest being
able to continue normal operation.

In Ethernet by comparison, a fault
occurring in a cable repeater can seri-
ously handicap the network. This can be
critical in an office environment such as
a bank, insurance company, or airline
where hundreds of users may be de-
pending on a LAN for their data pro-
cessing needs.

On the Token-Ring LAN, data and
control is transferred using two different
frame formats, as illustrated in Fig.3.

There are eight levels of priorities
which affect the ability of a DTE to
transmit its frames. For example, once a
DTE receives the token it checks the
current priority level against the priority

level of its frames. If the priority is
equal or less than that of the frames,
the DTE can readily transmit. If the
priority level is higher than the frames
awaiting transmission, the token is
passed on.

Before being passed, a priority re-
quest can be initiated in the token if the
existing priority level is lower than the
required level. Assuming no_ higher
level requests are made, the requesting
DTE can transmit its frames on the next
possession of the token. The number of
frames that can be transmitted by a
DTE depends on the maximum time al-
lowed for holding the token and the pri-
ority of the frames to be transmitted.

Having a priority system offers advan-
tages for real time applications since it
allows a set of frames to be sent concur-
rently by setting a high priority.

By comparison, Ethernet’s bus access
is probabilistic (it cannot be assured).
Thus, real time applications such as
voice are not possible. As the speed of
the token-ring LAN standard increases,
voice and data integration could become
more prominent.

A summary of the various features of
Ethernet, MAP and the IBM token-ring
is outlined in Table 1.

To be continued.

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050

Part 2: how to use the simple
p Amp Tester

Last month we described the circuit and
construction of the Op Amp Tester. In this
article we detail the various parameters which
can be tested and show how to check out

typical op amps.

by JOHN CLARKE

Although there are many parameters
that the Op Amp Tester can measure,
the basic technique for each measure-
ment relies upon only a few simple
operations. These involve adjusting the
potentiometers, taking readings from a
multimeter and then using a calculator
to find the result.

Last month we gave a list of specifica-
tions for some typical op amps and most
of those parameters mentioned can be
measured by the Op Amp tester. Be-
fore describing how to do each test, let
us define the relevant parameters.

Definition of terms

© Input Offset Voltage is the voltage
which must be applied between the in-
verting and non-inverting inputs of an

op amp through two equal resistances to
give a zero output voltage.

An ideal op amp would not require
any input offset voltage for a zero out-
put and most op amps have a typical
offset of only a few millivolts. Many op
amps provide terminals for offset ad-
justment using a trim potentiometer.
This adjustment can reduce the offset to
very close to zero.
© Input Bias Current is the average of
the currents to the inverting and non-in-
verting inputs of an amplifier.

The current into each input is mea-
sured, added together and divided by
two. Some op amps such as those with
Fet input stages have an extremely low
input current ranging from a few pi-
coamps up to a few nanoamps. An
input current of a few picoamps ap-

4£4).0P AMP TESTER

@~— OFF OUTPUT

2VAC

og | ba
EXT ry Lik
Rg

OFFSET =
ADJUST

AY,

cone FINE

tans
eese

OFFSET
INPUT

METER NULL |
Vin |

COARSE

Vin x 1000

ae
METER TO
_ ee VOLTMETER

Fig. 1 INPUT OFFSET VOLTAGE

Fig.1: use this setup to measure the input offset voltage

96 ELECTRONICS Australia, June 1987

proaches the ideal.

© Input Offset Current is the difference
between the two currents when the out-
put is zero.

This is due to the inevitable differ-
ences between the differential input
transistors in the first stage of the op
amp.

e@ Input Resistance is defined as the
change in input voltage versus the
change in input current, with one input
grounded. This is the differential mode
input impedance.

© Large Signal Voltage Gain is the ratio
of the change in output voltage for a
change in input voltage.

© Common Mode Rejection Ratio is the
ratio of the common mode input (both
inputs together) voltage range to the
change in input offset voltage over this
range. It is equal to the gain with a sig-
nal applied to only one input, divided
by the gain with the signal applied to
both inputs. It is normally expressed in
decibels.

© Power Supply Rejection Ratio is the
ratio of the change in input offset volt-
age to the change in power supply volt-
age. It can be measured by noting the
change in output voltage for a given
change in supply voltage and comparing
the result with the equivalent change in
input offset voltage.

@ Supply Current is the current re-
quired from the power supply to oper-
ate the amplifier, with no load con-
nected to the output.

© Common Mode Input Voltage Range
is the range of input voltage with both
inputs together over which the amplifier
Operates. Depending on the manufac-
turer, the op amp may or may not oper-
ate within specifications for the whole
common mode input range.

Exceeding the common mode input
range may cause the op amp to “latch
up” (ie, the output may go high or
low), or may cause damage to the de-
vice,

OFFSET
ADJUST

POWER

ca

This photograph shows a typical test setup. The op amp is plugged into the socket and wires used to make the circuit connections.

© Output Voltage Swing is the peak-to-
peak voltage swing which the op amp
can deliver without clipping.

e Bandwidth is the frequency where the
open-loop voltage gain (ie, without any
applied negative feedback) is reduced
by 3dB from the DC gain value.

e@ Unity Gain Bandwidth is the fre-
quency at which the open-loop gain of
the amplifier is reduced to one. This
can be measured using a frequency gen-
erator and an oscilloscope.

Measurement

Any op amp which can be powered
from a +12V supply can be safely
tested in the Op Amp Tester. For op
amps which are rated for higher supply
voltages, (eg, #15V), it is possible to
power the tester using an external sup-
ply. This supply voltage is connected to
the positive, negative and ground power
terminals on the Op Amp Tester. The
power switch is set to the EXT position
for external supply use and in the
12VAC position when powering from a
plugpack.

Insert the op amp package into the
middle row of the test socket. The outer
row of the sockets is used for connecti-
ing between the tester terminals and the
Op amp pins using single strand insu-
lated copper wire. Fig.2 on page 55 of

last month’s issue shows the pin-outs for
some single, dual and quad op amps.
Use this information when connecting
up the op amp.

Figs.1 to 5 show typical test set-ups
for an 8-pin Minidip version of a 741 op
amp. The accompanying photo portrays
the test set-up of Fig.1.

Power supply connections should be
made to the op amp from the + and —
power terminals of the tester. Single
supply op amps such as the CA3130
which can only be operated up to 16V
total should be powered by connecting
ground to the negative supply pin of the
op amp and the plus power terminal to
the positive supply pin of the op amp.

Only one op amp can be tested at a
time so that a quad or dual packaged op
amp will require testing of each op amp
separately.

Initially, connect the inverting or non-
inverting terminal of the op amp to the
ground terminal via a 10k resistor.
We will call this resistor Rg. The offset
terminal connects via a 10k. resistor,
called Ro, to the remaining input termi-
nal of the op amp. Connect the output
of the op amp to the output terminal of
the tester and finally connect a multime-
ter across the meter terminals of the
tester.

Measurement of the op amp DC pa-

rameters involves using of the Vin
x1000 amplifier, watching the output in-
dicator LED, adjusting the offset and
null controls, and measuring voltages at
the meter terminals, op amp output ter-
minal and supply rails. Note that if an
analog meter is used, the connecting
leads may need to be reversed depend-
ing upon the polarity of the output volt-
age. A digital multimeter will not re-
quire reversal due to its automatic po-
larity indication.

As its name suggests, the x1000 am-
plifier multiplies voltages measured at
the Vin input terminal by 1000. This is
very useful for obtaining greater resolu-
tion from your multimeter and also for
minimising loading effects (particularly
at the input terminals) during measure-
ment.

Let’s now detail how some of the
more important op amp parameters can
be measured.

Input Offset Voltage

To measure Input Offset Voltage,
connect the Vin terminal to the Offset
Input terminal and set the meter null
switch to the ground position. Set the
Offset Adjust fine control to the centre
of its rotation and apply power (see
Fig.1).

At this stage, the output indicator

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LED should be showing red (the op
amp output is low) or Green (the op
amp output is high). Adjust the Offset
Adjust coarse control until it is set very
close to the point where the output
LED turns off. Now adjust the fine con-
trol until the output LED goes out.

The adjustment of the fine offset ad-
just control may be very critical. In
particular it is difficult to set very high
gain op amps to zero output but quite
easy with lower gain types such as the
TLO61.

In practice, it is only necessary to set
the offset control to the switch-over
point where the output swings from one
level to the another to obtain a reliable
result. Putting it another way, since the
open-loop gain of op amps is so high, it
is only necessary to adjust the input off-
set voltage to bring the op amp output
voltage to approximately zero. Making
it spot-on zero does little to increase the
overall accuracy of the measurement.

The voltage measured by the mul-
timeter is the input offset voltage multi-
plied by 1000. For example, supposing
we get a reading of 2.18V on the mul-
timeter. Since this has been multiplied
by 1000 then the actual input offset
voltage is 2.18mV.

Note that readings above about 7.7V
at the “Vin x 1000” terminal” are not
accurate since the output of op amp IC2
will not swing much beyond this. In
cases like these, the measurement will
need to be made directly from the offset
input rather than through the x1000
meter circuit.

Input Bias Current

Input Bias Current for each input is
calculated by measuring the voltage
across each of the 10k input resistors
to the op amp.

Fig. 2. shows the connections to mea-
sure the input bias current for both in-
puts. The procedure is to first measure
the current at the Rg resistor input —
connect Vin to the op amp side of the
Rg resistor and ensure that the Meter
Null switch is down. Make sure that the
offset controls are set so that the op
amp output is close to zero and make a
note of the voltage measured on the
meter. The current is simply the voltage
at the op amp input (voltage at the
meter/1000) divided by 10kQ.

For our example 741 op amp we mea-
sured 384mV on the meter which gives
an actual voltage of 384 microvolts
across the 10k resistor. The input cur-
rent is therefore 38.4 nanoamps.

Next, measurements are made to find
the voltage across Ro. The input offset
current is then calculated as before.

Eq. 0P AMP TESTER

OFFSET
ADJUST

POWER =

UR: ' ) | Lf
JER ‘\ a ie METER,

METER NULL

COARSE

FINE
Vin x 1000

TO
VOLTMETER

a
OFFSET =
INPUT

Fig. 2 INPUT BIAS CURRENT

Fig.2: this diagram shows how to check the input bias current.

Firstly, the Meter Null is placed in
the up position and Vin is connected to
the Offset input (dotted line “b”).
Make sure that the Offset Adjustment
is set so that the op amp output is close
to zero. Now adjust the coarse and fine
controls of the meter null for a zero
reading on the meter.

This nulls out the offset voltage so
that a direct reading at the op amp side
of Ro can be the basis of current calcu-
lation.

Connect Vin to the op amp side of
Ro (dotted line ‘‘c’””) and read the volt-
age indicated on meter.

We measured 440mV across Ro for
our sample 741 op amp which corre-

sponds to 440V across the 10kQ resis-

tor. Thus the current is 44.0nA.

The input bias current specification is
then half the sum of the two bias cur-
rents for each op amp input.

For our test op amp the input bias
current is (38.4nA + 44.0nA)/2 =
41.2nA.

Note that the measurement is only ac-
curate for op amps with bias currents

4). 0P AMP TESTER

e@—— RED/GREEN OUTPUT

OFFSET
ADJUST

POWER

greater than about 10nA since the load-
ing of the Vin terminal can affect the
current flowing when connected directly
at the op amp inputs.

Input Offset Current

Input Offset Current is the difference
between the input current at the invert-
ing input and input current at the non-
inverting input.

For our test op amp, the Input Offset
Current is 44.0nA — 38.4nA = 5.6nA.

Large Signal Voltage Gain

Large Signal Voltage Gain is calcu-
lated by measuring the offset voltage re-
quired to set the output of the test op
amp to about 2V less than the positive
supply voltage. The reason for only set-
ting the output within 2V of the supply
is to ensure that the output of the op
amp is not clipping.

The measurement is easily done using
two meters, although a single one can
be used by quickly changing the meter
probes as shown in Fig.3.

Connect the op amp as shown in
Fig.3 with the meter connected to the

METER NULL

COARSE

TO
Vou TineTER

~
VOLTMETER
_

OFFSET

INPUT

Fig. 3 LARGE SIGNAL VOLTAGE GAIN

Fig.3: the large signal voltage gain can be measured using the setup shown here.

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Op amp output (dotted lines ‘“‘a’”). Ad-
just the Offset controls so that the op
amp swings positive to some convenient
voltage at least 2V below the positive
supply rail. We set the output to +6V
on our test 741.

Now transfer the meter to measure
the offset voltage by connecting it
across the “Vin x 1000” output termi-
nals (dotted lines “‘b”). Make sure that
the meter null switch is up. Adjust the
meter null knobs for a zero reading.

Now measure the offset voltage. We
measured 15mV on the meter which
corresponds to 15mV/1000 = 15yV for
the op amp.

The large signal voltage gain is then
calculated by dividing the op amp volt-
age output swing by the measured offset
voltage. For our 741 op amp example,
dividing 6V by 0.015 gives a result of
400V/mvV.

Power Supply Rejection
Ratio

The PSRR is measured using an ex-
ternal power supply which can be ad-
justed from +12V to £15V or greater.
The setup is shown in Fig.4.

Set the power supply to +15V and
set the offset controls for a zero op amp
output with the LED off. Now set the
meter null controls so the meter reads
OV.

Adjust the power supply to £12V
and adjust the offset controls for a zero
output on the op amp. Note the reading
shown on the meter.

The change in offset voltage in micro-
volts (which is simply the offset reading
just taken) divided by the change in
power supply volts (6V) gives the PSRR
in pV/V.

For our test 741 op amp, we obtained
25mV on the meter or 25uV for the
change in offset voltage. Thus the
PSRR is 25/6 or 4uV/V.

Supply Current

The supply current is simply mea-
sured by connecting a multimeter in
series with one of the supply connec-
tions to the op amp and disconnecting
the output so that the op amp does not
drive the LED. The “‘per op amp cur-
rent” is the measured current divided
by the number of op amps in the pack-
age.

We measured 1.1mA for the test 741
op amp.

Input Resistance

This parameter can only be measured
for op amps with input resistance less
than several megohms. Op amps with
Giga or Tera ohm input resistance can-

4E4).0P AMP TESTER

o——OFF

oe

EXTERNAL |
POWER GND
SUPPLY |

-V

(a) +15V
(b) 212V OFFSET POWER
ADJUST

METER NULL

OUTPUT Vin
COARSE

Vin x 1000

Fig. 4 POWER SUPPLY REJECTION RATIO

Fig.4: here’s how to check the power supply rejection ratio.

not be measured in this set up. Of
course an op amp which claims a very
high input resistance and measures a
very low value can be considered faulty.

Connect the tester as shown in Fig.5
(dotted line “a’”) with the meter null
switch in the upward position and Vin
connected to the offset input. Adjust
the offset controls so that the output
LED shows green. Adjust the meter
null control for zero reading on the
meter.

Now connect Vin to the op amp input
(dotted line ‘“‘b’”) and take the reading.
The current is the (voltmeter
reading/1000) divided by 10k.

For our test 741 op amp, we mea-
sured 440uV across the 10k resistor.
The current was therefore 44nA.

Next, reconnect the Vin to the offset
input terminal (dotted line ‘‘a”) and ad-
just the offset controls so that the out-
put LED indicates red. Make a note of
the offset voltage on the meter. For the
test op amp, we obtained 640mV/1000
or 640uV at the offset input.

Null this reading on the meter using

Eq). OP AMP TESTER

@~—— RED GREEN OUTPUT

OFFSET
ADJUST

AM,

the meter null controls and measure the
voltage across the 10k, resistor by con-
necting the Vin terminal to the op amp
side of the 10k© resistor (dotted line
“b”). Calculate the current.

For our test op amp, we obtained
425mV or 425zV across the 10k© resis-
tor. This gives 425/10k or 42.5nA.

Input resistance is the change in the
applied input voltage divided by the
change in input current.

So for our test op amp we changed
the input voltage by 640uV and had a
change in input current of (44 —
42.5)nA = 1.5nA. The input resistance
is therefore 640uV/1.5nA = 427kQ.

This completes our outline of proce-
dures for the Op Amp Tester although
it can doubtless be used to measure
other parameters such as Common
Mode Rejection Ratio, Output Imped-
ance, Short Circuit Output Current and
so on.

Incidentally, all parameters measured
for the test op amp were within speci-
fications for the 741 as published in
Fig.2 last month.

METER NULL
Vin
COARSE

FINE
Vin » 1000

METER} To

| VOLTMETER
. |

Fig 5 INPUT RESISTANCE

Fig.5: wiring diagram for checking the input resistance.

ELECTRONICS Australia, June 1987

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An introduction to hifi, Pt.14

FM radio tuners —

Antennas; survey of receivers;

demodulation

Having examined the basic principles of high quality FM
sound broadcasting, it now remains to explain how the
incoming signal is processed in typical FM tuners to recover
the original left and right-channel stereo information. The
explanation covers both valve and solid state design practice.

by NEVILLE WILLIAMS

Perhaps the logical place to begin is
with the radiated signal and the receiv-
ing antenna.

Without going into a lot of detail, it
can be stated that the energy in a radio
wave, as it travels through space, is evi-
dent as an electric field and a magnetic
field at right angles to each other and to
the direction of propagation — as illus-
trated in Fig.1.

The attitude of the respective fields,
relative to the ground, is referred to as
the “polarisation” of the wave, standard
practice being to equate it to the elec-
tric component. Thus, if the electric
field, as it leaves the transmitting anten-
na, is (1) at right angles, or (2) parallel
to the surface of the earth, the transmis-
sion is said to be (1) vertically or (2)
horizontally polarised.

Polarisation is determined principally
by the configuration of the transmitting
antenna (see station list, EA March
1986, p.71) but it can be modified, en
route, by local topography, street cables
and large metal structures.

For best reception on the FM broad-
cast band (88-108MHz) the transmitting
and receiving antennas should have the
same polarisation but herein lies a prob-
lem:

For portable and automotive FM re-
ceivers, the receiving antenna normally
has to be a near vertical whip — which
means that, ideally, transmisssions also
to be vertically polarised. But this con-
flicts with the interests of the majority
of listeners who may wish to use the

104

ELECTRONICS Australia, June 1987

one antenna for FM and TV, because
most TV services in Australia call for
horizontal polarisation.

As a compromise, most FM broadcast
stations in this country have settled for
so-called ‘‘mixed”’ polarisation which, in
effect, tilts the vectors (of Fig.1) with
the purpose of sharing the radiated
energy deliberately, rather than ran-
domly, between vertical and horizontal
receiving antennas.

Owners of portable and automotive
FM receivers have little choice but to
use them with the associated telescopic
whip, wherever they happen to be. For-

ELECTRIC
FIELD

MAGNETIC
FIELD

—_—
DIRECTION
OF WAVE

Fig.1: diagram depicting the relationship
between the electric and magnetic fields in
a VHF radio wave. Vertical polarisation is
shown but it could be otherwise, as ex-
plained in the text.

tunately, within the main service area of
FM transmitters, the signal strength is
normally adequate for casual listening.
(Ferrite rod or small frame antennas,
commonly used on the MW broadcast
band, are not a proposition at VHF).

For domestic hifi installations, listen-
ers are usually more demanding, partic-
ularly in respect to signal/noise ratio,
and this commonly calls for a more am-
bitious antenna system, capable of
providing a stronger input signal.

Where cost and space permit, the
ideal provision is a separate, directional
outdoor antenna for the FM tuner. FM
antennas are superficially similar to TV
antennas and are commonly available
through the same suppliers, but their di-
mensions are optimised for the FM
band.

Where the FM and TV stations lie in
the same general direction, an FM tuner
or receiver can usually be connected to
an existing outdoor TV antenna — but
it needs to be done properly. First
check the antenna and its present TV
cabling to ensure that it is in good
condition and then use a commercial
“signal splitter” to interconnect the new
(FM) cable with the old.

These days, most outdoor TV anten-
nas use 75-ohm coaxial cable to connect
to the TV receiver and the logical
course is to use a 75-ohm splitter and
similar cable, terminated by a standard
antenna plug, to feed the FM tuner.
The chances are that the tuner (or re-
ceiver) will have a matching antenna
socket or terminals at the rear marked
“75 ohms’’.

Some tuners may, however, have a
pair of terminals marked ‘300 ohms”’.
No hassle: most electronic parts suppli-
ers stock 75/300 ohm balun adaptors
and can explain how they are fitted.

In high signal strength areas, an inex-
pensive indoor FM antenna can be con-

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Fig.2: an inexpensive FM antenna system
can be contrived from a few metres of 300-
ohm TV twin “‘ribbon’’. For indoor use,
the white translucent variety is less obtru-
sive.

trived from a few metres of 300-ohm
TV twin lead, as shown in Fig.2. This
should be supported horizontally, at ap-
proximate right angles to the direction
from which the FM signals are coming.
It can be strung out-of-sight between
rafters under a tile roof, or pinned to a
wooden picture rail. By using the for-
mula shown, the antenna can be cut to
resonate at — or favour — the fre-
quency of a particular station but,
otherwise, 147cm (approx.) is a suitable
mean figure.

Where the local FM stations are
known to be using vertical polarisation,
the antenna should be supported veri-
cally, with the connecting lead taken
away at right angles for a metre or so,
before running down to the FM tuner.

Basic FM receiver

FM tuners and receivers are — and
always have been — based on the su-
perheterodyne principle, as outlined in

a] TUNED RF IF
AMPLIFIER ¥ x AMPLIFIER
OSCILLATOR

the earlier chapter on AM-stereo receiv-
ers. There are important differences
though, as will become apparent from
the block diagram, Fig.3. We will take
an initial look at the various stages, by
way of orientation!

Consistent with the foregoing re-
marks, the antenna input is shown as
providing for either or both a 75-ohm
unbalanced (coaxial) cable and a 300-
ohm balanced twin lead.

The incoming signal is fed first to one
(sometimes two) RF amplifier stages
with input and output circuits tuneable
to the desired station carrier. The RF
amplifier section has four main func-
tions, namely to:

1. Pre-select the wanted carrier and at-
tenuate other signals which might cause
“image” or other interference problems;
2. Amplify the incoming signal before it
encounters the somewhat noise-prone
frequency changing stage.

3. Isolate the antenna from the receiv-
er’s internal oscillator;

4. Provide a means by which the AGC
(automatic gain control) system can at-
tenuate unduly strong input signals.

A prerequisite of the RF amplifier
section is that it should exhibit an over-
all bandpass of around 250kHz, in order
not to attenuate the essential signal
sidebands. Whereas, in an AM system,
loss of the outer sidebands causes loss
of treble response, the effect on an FM
system is to compress the modulation
peaks, resulting in harmonic distortion
of louder sounds.

From the RF amplifier section, the
signal passes to a frequency changing
(or “mixer”) stage where it is hetero-
dyned or mixed with the output from
the in-built tuneable oscillator, men-
tioned above, to produce a “difference”
resultant, the so-called intermediate fre-
quency or “IF”.

TUNING
INDICATOR
FM
IDEMODULATOR}

STEREO
DECODE

STEREO
INDICATOR
SWITCH

A figure of 455kHz, as used in AM
receivers, is totally unsuitable in a cir-
cuit where the required bandpass is it-
self about half that figure. For FM
tuners and receivers, the IF has been
standardised worldwide at 10.7MHz —
a frequency that is kept free for that
purpose.

Assuming that the local oscillator op-
erates above the incoming signal fre-
quency by that figure, it needs to be
tuneable from 88+10.7 to 108+10.7 or
from 98.7 to 118.7MHz.

Even though operating at 10.7MHz,
considerable care is still necessary in the
design and/or adjustment of the IF am-
plifier system to ensure that the selec-
tivity curve is not unduly “‘peaky” and
that the overall bandpass is, again, wide
enough to accommodate what we re-
ferred to in the last article as the “‘side-
bands that matter’.

While the bandpass is important in an
FM tuner, the linearity in terms of sig-
nal overloading is not. In fact, the
“limiter” stage (or stages) included in
most FM tuners are essentially IF am-
plifier stages which are deliberately set
up and over-driven so that they will
overload, even when handling what
were originally very weak signals. In so
doing, they have the “clipping” effect,
illustrated in Fig.3 of the previous arti-
cle, virtually eliminating redundant AM
(noise) components but retaining the
FM information.

The AGC voltage must be derived
from the IF signal before clipping, while
it is still subject to variations in ampli-
tude. For this reason, it is shown as
being picked up part way along the IF
amplifier.

The FM demodulator, which follows
the IF section, is equivalent to the de-
tector in an AM tuner, although func-
tioning in a quite different manner. It

AUDIO
AMPLIFIER

AUDIO
DE-EMPHASIS

AUDIO
AMPLIFIER

Fig.3: the basic circuit functions in an FM superhet tuner/receiver, valid for both valve and solid-state technology. Modern designs
contain extra modules for digital control and readout, which has taken over from analog tuning and dials.

ELECTRONICS Australia, June 1987 105

We're talking about the exciting David
Tilbrook designed speaker kit which
uses VIFA's high performance drivers
from Denmark; his 2-way, digital-ready
100 Watt capable masterpiece. The
name Tilbrook is synonymous with
brilliant design and performance
characteristics and this system keeps
the legend alive and well. When you
compare the price of this kit with similar,
fully imported loudspeakers, you will be
saving from 55% to 60%!

The performance of the speakers is
outstanding. Australian Hi-Fi
Magazine recently acclaimed: ‘‘Well,
Mr Tilbrook and Scan have certainly
done their homework. The AEM -6102
is simply superb. A very accurate
design and exhibits remarkable low
levels of colouration and distortion -
across the board."

Such performance can only be
achieved when every component is just
right and the drivers are of advanced
construction. Which is why VIFA drivers
are chosen for such fine speakers as
MISSION, DALI, ROGERS, JAMO,
VANDERSTEEN, HEYBROOK, BANG
& OLUFSEN, D.C.M. and MAGNAT just

AEM-6I02
KIT SPEAKERS.

to mention a few.

Nearly a thousand of the AEM 6102
speakers have already been built in
Australia with superb results. For only
$799 a pair including drivers, pre-built
cross overs and flatpack cabinets you
can be the owner of one of these sonic
masterpieces.

For more information, please write to:
Australian Sole Distributor:

SCAN AUDIO Pty. Ltd.,

52 Crown Street, Richmond, 3121.
Telephone (03) 429 2199. Telex 39201.

Genuine O.E.M. enquiries welcome.

Stocked and demonstrated by:
NSW: All Jaycar Stores (02) 267 1614.
QLD: Jaycar, Buranda (07) 393 0777.
Qld Stereo/Visual (07) 37 7433,
VIC: Radio Parts (03) 211 8122.
Rod Irving Electrs. (03) 663 6151
TAS: NWS Hi Fi, Burnie. (004) 31 5633.
Quantum, Hobart. (002) 31 0088.
SA: Eagle Electronics (08) 271 2885.
International Sound (08) 212 5006
Miltronics (08) 42 3781.
WA: Alberts Hi Fi, Perth (09) 322 4409.
NT: Sound Spectrum, Darwin (089) 81 5060.

THIS ISN’T COMMON
KNOWLEDGE

Never before has the University of New South Wales offered a
range of vocational courses such as those embodied in the
forthcoming Winter Professional School. If you’re an ambitious
Engineering Professional and you want to update your knowledge in
key areas, then find out more about these courses:

¢ DRY ETCHING FOR MICRO-ELECTRONIC

APPLICATIONS

ASSEMBLY LANGUAGE PROGRAMMING
DESIGN OF SWITCHED-MODE POWER SUPPLIES
DIGITAL COMMUNICATIONS

OPTICAL FIBRE COMMUNICATIONS
COMPUTER METHODS IN ENGINEERING AND

SCIENCE

Phone now (02) 697 3175...

... OF write to Continuing Education, University of New South Wales,

PO Box 1, Kensington 2033.

i
Vendy!

et] THE UNIVERSITY OF

Pe

ELECTRONICS Australia, June 1987

NEW SOUTH WALES

AT LEAST
+75kHz

e
>
a
=
2
°

—s——- FREQUENCY ———

Fig.4: the input/output ‘‘S-curve’’ for an
FM discriminator or ratio detector. The in-
coming IF signal must be centred on the
straight section, avoiding the outer slopes.

demodulates the FM carrier to recover
the audio signals imposed upon it and
performs other supplementary tasks
such as providing an AFC (automatic
frequency control) voltage to stablise
the oscillator, and the drive signal for a
tuning indicator.

In the case of a mono tuner, the
audio signal from the demodulator
would pass through a top-cut filter net-
work, to provide the necessary de-em-
phasis (Fig.5, previous chapter) and
then on to the audio amplifier. In a
stereo tuner, however, the demodulated
multiplexed signal is fed to a stereo
decoder stage and is de-emphasised only
after having been resolved into the left
and right-channel audio components.

Early receiver problems

In the era of valves and their associ-
ated technology, early model FM tuners
were finicky to design, adjust and use
and as often as not, were better suited
to enthusiasts than to ordinary listeners.
Tuning, for example, tended to drift no-
ticeably as the local oscillator and other
ciruitry warmed up after switch-on.

In the longer term, IF transformers
often drifted out of adjustment because
of temperature, vibration and ageing
problems, thereby affecting the shape of
the passband. Adding to their vulner-
ability, 10.7MHz and 455kHz IF trans-
formers were connected in series in
some FM/AM receivers, as an economy
measure, to allow the same IF amplifier
valves to be used for both modes.

But, most confusing of all, early FM
receivers used either a Foster-Seeley
discriminator or the commonly pre-
ferred ratio detector for demodulation,
both being dependent on the critical
phase/frequency relationships in an as-
sociated, specially configured IF trans-
former. The design objective was a sym-
metrical input/output ‘“‘S-curve”, as de-
picted in Fig.4.

The midpoint of the “S” would ide-
ally coincide with the centre of the

overall IF bandpass characteristic (ie,
10.7MHz). As the carrier deviated by
up to 75kHz either way, displacement
along the “straight” centre portion of
the “S” would result in a plus or minus
output voltage, representing the re-
covered audio signal.

Unfortunately, inadequate design,
maladjustment or drift relative to the IF
passband could all too easily result in an
S-curve which was effectively far less
symmetrical and less linear than the
ideal, resulting in perceptible distortion
during modulation peaks.

Tuning could also be confusing for
the uninitiated because, with a conven-
tional manual system, the correct tuning
position was flanked by two spurious —
and distorted — settings where the sig-
nal could be partially demodulated by
one or other of the outer ends of the
S-curve.

No less disconcerting, many early FM
tuners generated a high level of noise
when tuning between stations. This
came about because, with no input sig-
nal, there was nothing to drive the
limiter stages into overload; so, instead
of clipping residual noise, they ampli-
fied it!

Towards the end of the valve era,
more refined design and AFC largely
overcame the drift problems, automatic
muting silenced the inter-station noise,
and development of the 6BN6 quadra-
ture detector signalled a less tedious ap-
proach to FM demodulation. Improved
valves and more ambitious circuit tech-
niques boosted overall performance,
such that the last generation of pre-
dominantly valve AM/FM stereo receiv-
ers were quite impressive pieces of
equipment, even if rather massive.

Sansui’s Model 1000A receiver, for
example, offered all of the facilities
available in its present-day solid-state
equivalents, even to wide/narrow AM.
Rated power output was 40+40W RMS
at around 1% distortion — but at an
all-up weight of something over 20kg.

The solid state era

In the early and mid-70’s, transistors
and first generation ICs, along with
matching small components, changed
the scene dramatically. While the new
wave of solid-state FM tuners and re-
ceivers still relied on manual tuning
with composite 4 or 5-gang variable ca-
pacitors, the orderly layout of miniature
components on PC boards was a far cry
from the congested interior of conven-
tional hard-wired valve equipment.

Typical of the new look was JVC’s
model 5515X AM/FM stereo receiver,
reviewed in the July 1975 issue of EA.

| wrtine
| AMPLIFIER

SIGNAL
SPLITTER
90° PHASE

SHIFT

GATED
SYNCHRONOUS,
DEMODULATOR] |

Fig.5: much simplified, this diagram gives some idea of the operation of a quadrature FM
demodulator, providing audio output, AFC voltage and drive for tuning meters of one

kind or another.
Although somewhat less pretentious
than the Sansui 1000A, with a measured
power output of 25+25W RMS at 0.3%
distortion, it weighed in at a much more
manageable 9kg. °

Around the same time (Nov. 1974),
EA described an AM/FM stereo tuner
for home construction based on a
Heathkit pre-packaged kit (Model AJ-
1214). This, too, used a conventional
tuning dial and 5-gang tuning capacitor
but the rest of the circuitry was indica-
tive of the shape of things to come.

The tuner was housed in a case mea-

suring 330 x 280 x 90mm (W x D x H) .

and weighed a mere 3.5kg. Inside, the
two tuners shared a common PC board,
as pictured, measuring about 180 x
170mm and occupying less than half the
available area. While conservative by
present standards, it represented a
quantum leap compared with the valve
technology that preceded it.

Referring back to the various func-
tions depicted in Fig.3, the Heathkit
AJ-1214 used a single FET (field effect
transistor) as a tuned RF amplifier, with
AGC voltage applied to its gate elec-
trode.

High frequency NPN _ transistors
served as mixer and local oscillator
stages, with the oscillator tuning subject
to automatic correction by means of a
“varicap” (or “varactor’”’) diode — sig-
nifying variable capacitance or variable
reactance — connected in parallel with
the main tuning capacitor and con-
trolled by an AFC voltage from the
quadrature detector. The AFC system
counteracts initial tuning errors and/or
frequency drift by nudging the oscillator
frequency up or down, as necessary, to
maintain the IF signal at the intended
intermediate frequency — nominally
10.7MHz.

Varicap diodes are basically similar to
the normal silicon rectifier type, except
that the junction impurity concentration
is manipulated so as to:

1. Optimise the change in capacitance
across the junction when it is subjected
to a varying reverse voltage, and

ELECTRONICS Australia, June 1987

2. Minimise series resistance losses and
therefore maximise the “‘Q” of the junc-
tion capacitance.

IF amplifier section

In place of one or more valves or
transistors, interconnected by double-
tuned IF transformers, the IF amplifier
system in the Heathkit tuner was con-
centrated around a single multi-purpose
Motorola MC1357P IC and_ two
matched 10.7MHz ceramic filters, one
at its input, the other at its output. Such
filters greatly reduce dependence on
conventional IF transformers and, if
correctly chosen, ensure the required
bandpass characteristic, with commend-
able phase linearity.

Ceramic filters (or ceramic resona-
tors) are piezo-electric devices which,
like the traditional quartz crystal, ex-
hibit a mechanical resonance reminis-
cent of a high-Q electrical tuned circuit.
They are processed from selected
ceramics (eg. lead-zirconate-titanate)
and factory calibrated for filter service.
Along with varicaps, they have revolu-
tionised tuner and receiver design.

The MC1357P IC provided the neces-
sary IF gain, along with two separate
outputs; one suitable for buffering and
rectification to generate an AGC volt-
age for the RF amplifier; the other, lim-
ited to remove the AM noise and ready
to feed to the FM demodulator stage.

Quadrature demodulator

A second MC1357P was intercon-
nected to function as a quadrature
demodulator — a role in which it pro-
cesses two versions of the incoming IF
signal “in quadrature”, signifying a
phase difference of 90 degrees.

In this role, as illustrated in Fig.5, the
basic feed from the IF system passes
through a section of the IC, operating
as a high-gain wideband limiting (or
clipping) amplifier, which transforms
the incoming signal into a train of es-
sentially rectangular pulses, of uniform
amplitude but retaining the frequency
modulation characteristics of the signal.

107

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A portion of the pulsed signal is
made available to be passed through an
external LCR resonant network and fed
back into the IC, now shifted in phase
by a nominal 90-degrees. A synchro-
nous demodulator combines the two
pulse trains to produce a resultant out-
put voltage that is dependent on their
relative phase relationship.

In practice, the system is set up so
that, with a signal centred in the IF
passband, the output has a certain
median value. However, if the incoming
signal deviates in frequency, the phase
angle between the respective inputs
varies and, with it, the resultant output
voltage.

If the frequency of the incoming sig-
nal varies rapidly, as with audio (or su-
personic) modulation, so also does the
output voltage — constituting, in fact,
the demodulated signal.

If, simultaneously, there is a tendency
for the average resultant voltage to
creep above or below the median value,
an overall shift in the incoming fre-
quency would be indicated. By diverting
some of the output signal through a
long time-constant RC filter, the audio
content can be eliminated and a DC
component isolated to serve as an AFC
voltage to control the local oscillator, as
already mentioned. If desired, the same
DC voltage can be used to operate a
centre-reading tuning indicator.

Multiplex decoding

And that brings us to the matter of
stereo decoding. This can be achieved

(a) L SIGNAL

(b) R SIGNAL
L+R

-(c) SUM: >

@ DIFFERENCE: +8

(e) DIFFERENCE SIGNAL
& 38kKHz

(f) DIFFERENCE SIGNAL,
38kHz, + SUM SIGNAL

by effectively reversing the encoding
procedures described in the last article.
It requires that the composite signal
from the FM demodulator be processed
through filters to once again isolate the
main L+R audio signal, the 19kHz pilot
tone and the two sets of L-R sidebands.

This done, the 19kHz pilot tone is
used to create or phase lock a locally
generated 38kHz carrier, which is duly
combined with the sidebands and
demodulated to recover the L-R audio
signal. Resistive matrixing of the sum
and difference signals can then isolate
the original L and R components for
normal stereo amplification.

While this is a legitimate method, it is
heavily dependent on resonant filters
and is not a very attractive proposition
for modern mass production.

The preferred approach is not to
separate the L+R audio and L-R side-
band components but to process them
in combination. Accordingly, the 19kHz
tone is separated out from the audio in-
formation — a relatively simple proce-
dure — leaving the latter as a seemingly
random mix of an audio (sum) signal
and the two sets of supersonic sidebands
relating to the difference signal.

But the mixture of signals is not as
random as it might appear — a point
that emerges when a phase locked
38kHz signal is added to the mix. In
fact, the positive and negative peaks of
the 38kHz wave add selectively to the
supersonic sideband excursions of the
composite signal, to produce what looks
like an oddly modulated carrier with

(g) COMPOSITE SIGNAL
AS RECOVERED

«h) PHASE LOCKED
38kHz

(i) LEFT & RIGHT
ACCESSIBLE

Fig.6: (a) to (d) are the left, right, sum and difference signals; (e) is the double sideband,
suppressed carrier version of (d); and in (f), L+R has been added to form the composite
audio signal. Diagrams (g) to (i) show how adding the 38kHz carrier to the composite sig-
nal separates the L and R components for easy recovery.

one side having the contour of the L
signal and other of the R signal.

Resorting to graphics, Fig.6 has been
adapted from the ‘Stereo FM Hand-
book” by P. Harvey and K.J. Bohlman,
both (at the time) lecturers at the Lin-
coln College of Technology, UK. Dia-
grams (a) to (f) suggest how the original
L and R signals add to produce the
composite resultant of L+R and a
twin-sideband version of L-R. Diagrams
(g) to (i) illustrate what happens when a
reconstituted 38kHz signal is added to
the mix, as described above.

The contours can be resolved sepa-
rately by envelope (AM) detection of
one kind or another as, for example, by
twin diodes, so polarised as to sense the
positive-going and negative-going peaks.

At this level, the process can be re-
garded as essentially analog “synchro-
nous” detection. Alternatively, the
diodes may be thought of as switches,
turned on by alternate half-cycles of the
38kHz signal and steering the left and
right components into the appropriate
output channel.

Taking the switching concept further,
the 19kHz pilot tone can be processed
into 38kHz and 76kHz rectangular
pulses for more precise timing and the
use of sample and hold techniques of-
fering, in particular, better L-R channel
separation.

Stereo decoding in the Heathkit tuner
was performed by a Motorola MC1310P
IC, based on the above switching tech-
nology. An internal voltage controlled
oscillator generates a 76kHz square
wave, which is divided down to 38kHz
and 19kHz, the latter being compared
with the incoming pilot tone and used
to phase lock the entire sampling and
switching system.

Because L and R samples are di-
verted alternately to the respective out-
put circuits, as described above, in ef-
fect, they constitute sampled signals,
with a pulse rate of 38kHz (compared
with 44.1kHz for compact discs). As
such, they must undergo not only de-
emphasis but also low-pass filtering to
remove all frequency components above
15kHz, in particular artefacts of the
pilot tone and the switching process.

(For a further discussion of the
MC1310P, see the description of an
FM Stereo Decoder by Jamieson Rowe
and David Edwards, EA April 1975).

In the next chapter, we will bring this
background material right up to date by
relating it to the recently described
Playmaster AM/FM Stereo Tuner. The
principles of pushbutton ‘‘digital” tuning
will also be covered. @

ELECTRONICS Australia, June 1987 109

| «Back by Popular Dem

DATA & REFERENCE

DIGITAL IC EQUIVALENTS AND PIN CONNECTIONS
A. Michaels BP0140
Shows equivalents and pin connections of a popular user-orientated
selection of European, American and Japanese digital ICs. Also
includes details of packaging, families, functions, manufacturer and
country of origin.

$18.00

256 pages (Large Format)

LINEAR IC EQUIVALENTS AND PIN CONNECTIONS
A. Michaels BP0141
Shows equivalents and pin connections of a popular user-orientated
selection of European, American and Japanese linear ICs. Also
includes details of functions, manufacturer, and country of origin.
$18.00
320 pages (Large Format)

INTERNATIONAL TRANSISTOR EQUIVALENTS GUIDE
A. Michaels BP008S
Helps the reader to find possible substitutes for a popular user-
orientated selection of European, American and Japanese
transistors. Also shows material type, polarity, manufacturer and
use.

$12.00

320 pages

CHART OF RADIO, ELECTRONIC, SEMICONDUCTOR AND
LOGIC SYMBOLS
M. H. Babani, B.Sc.(Eng) BP0027
Illustrates the common, and many of the not-so-common, radio,
electronic, semiconductor and logic symbols that are used in books,
magazines and instruction manuals, etc., in most countries
throughout the world.

$4.00

Chart

RADIO AND ELECTRONIC COLOUR CODES AND DATA
CHART

B. B. Babani BP0007
Covers many colour codes in use throughout the world, for most
radio and electronic components. Includes resistors, capacitors,
transformers, field coils, fuses, battery leads, speakers, etc.

$4.00
Chart
AUDIO AND HI-FI
BUILD YOUR OWN SOLID STATE HI-Fl AND AUDIO
ACCESSORIES
M. H. Babani BP0220

An essential addition to the library of any keen hi-fi and audio
enthusiast. The design and construction of many useful projects
are covered including: stereo decoder, three-channel stereo mixer,
FET pre-amplifier for ceramic PUs, microphone pre-amp with
adjustable bass response, stereo dynamic noise filter, loud-speaker
protector, voice-operated relay, etc.

$6.00

96 pages

AUDIO PROJECTS

F. G. Rayer BP0090
This book covers in detail the construction of a wide range of audio
projects. The text has been divided into the following main sections:
Pre-amplifiers and Mixers, Power Amplifiers, Tone Controls and
Matching, Miscellaneous Projects.

All the projects are fairly simple to build and have been designed
around inexpensive and readily available components. Also, to
assist the newcomer to the hobby, the author has included a number
of board layouts and wiring diagrams.

$8.50
96 pages
COMPONENT SPECIFIC
MODERN OP-AMP PROJECTS
R. A. Penfold BP0106

Includes a wide range of constructional projects which make use
of the specialised operational amplifiers that are available today,
including low noise, low distortion, ultra-high imput impedance, low
slew rate and high output current types. Circuits using
transconductance types are also included.
All of the projects are fairly easy to construct and a stripboard layout
is provided for most of them so that even constructors of limited
experience should be able to build any of the projects with the
minimum ot difficulty.

$8.50

112 pages

MODEL RAILWAY PROJECTS
R. A. Penfold BPO009S
The aim of this book is to provide a number of useful but reasonably
simple projects for the model railway enthusiast to build, based on
inexpensive and easily obtainable components.
The projects covered include such things as controllers, signal and
sound effects units, and to help simplify construction, stripboard
layouts are provided for each project.

$8.50

112 pages

AERIALS

AERIAL PROJECTS
R. A. Penfold BP0105
The subject of aerials is vast but in this book the author has
considered practical aerial designs, including active, loop and ferrite
aerials which give good performances and are relativiey simple and
inexpensive to build. The complex theory and mathematics of aerial
design have been avoided.
Also included are constructional details of a number of aerial
accessories including a pre-selector, attenuator, filters and tuning
unit.

$8.50

96 pages

25 SIMPLE AMATEUR BAND AERIALS

E. M. Noll BP0125
This concise book describes how to build 25 amateur band aerials
that are simple and inexpensive to construct and perform well. The
designs start with the simple dipole and proceed to beam, triangle
and even a mini-rhombic made from four TV masts and about 400
feet of wire.

You.will find a complete set of dimension tables that will help you
spot an aerial on a particular frequency. Dimensions are given for
various style aerials and other data needed for spacing and cutting
phasing lengths. Also included are dimensions for the new WARC

bands.
$6.50
80 pages

25 SIMPLE SHORTWAVE BROADCAST BAND AERIALS
E. M. Noll BP0132
Fortunately good aerials can be erected at low cost, and for a small
fractional part of the cost of your receiving equipment.
This book tells the story. A series of 25 aerials of many different
types are covered, ranging from a simple dipole through helical
designs to a multi-band umbrella.

$6.50

80 pages

25 SIMPLE INDOOR AND WINDOW AERIALS
E. M. Noll BP0136
Written for those people who live in flats or have no gardens or other
space-limiting restrictions which prevent them from constructing a
conventional aerial system.
The 25 aerials included in this book have been especially designed,
built and tested by Mr. Noll to be sure performers and give
surprisingly good results considering their limited
dimensions.

$6.00

64 pages

25 SIMPLE TROPICAL AND MW BAND AERIALS
E. M. Noll BP0145
Shows you how to build 25 simple and inexpensive aerials for
operation on the medium wave broadcast band and on 60, 75, 90
and 120 metre tropical bands. Designs for the 49 metre band are
included as well.

$6.00

64 pages

FAULT-FINDING

HOW TO GET YOUR ELECTRONIC PROJECTS WORKING
R. A. Penfold BP0110
The aim of this book is to help the reader overcome problems by
indicating how and where to start looking for many of the common
faults that can occur when building up projects.
Chapter 1 deals with mechanical faults such as tracing dry joints,
short-circuits, broken P.C.B. tracks, etc. The construction and use
of a tristate continuity tester, to help in the above, is also covered.
Chapter 2 deals with linear analogue circuits and also covers the
use and construction of a signal injectortracer which can be used
to locate and isolate the faulty areas in a project.
Chapter 3 considers ways of testing the more common components
such as resistors, capacitors, op amps, diodes, transistors, SCRs,
unijunctions, etc., with the aid of only a limited amount of test
equipment.
Chapter 4 deals with both TTL and CMOS logic circuits and includes
the use and construction of a pulse generator to help fault-finding.
$8.50
96 pages

TRANSISTOR RADIO FAULT-FINDING CHART BPO070
C. E. Miller

Used properly, it should enable the reader to trace most
common faults reasonably quickly. Across the top of the chart
will be found four rectangles containing brief descriptions of
these faults, vis — sound weak but undistorted, set dead.
sound low or distorted and background noises. One then
selects the most appropriate of these and following the
arrows. Carries out the suggested checks in sequence until
the fault is cleared Chart $4.00

ELECTRONIC & COMPUTER MUSIC

ELECTRONIC MUSIC PROJECTS

R. A. Penfold BPOO74
Provides the constructor with a number of practical circuits for the
less complex items of electronic music equipment, including such
things as fuzz box, waa-waa pedal, sustain unit, reverberation and
phaser units, tremelo geneator, etc.

The text is divided into four chapters as follows:

Chapter 1, Guitar Effects Units; Chapter 2, General Effects Units;
Chapter 3, Sound General Projects; Chapter 4, Accessories.
$9.50
112 pages

ELECTRONIC SYNTHESISER CONSTRUCTION
R. A. Penfold BP0185
Should enable a relative beginner to build, with the minimum of
difficulty and at reasonably low cost a worthwhile monophonic
synthesiser, and also learn a great deal about electronic music
synthesis in the process. This is achieved by considering and
building the various individual parts of the circuit that comprise the
whole instrument as separate units, which can then be combined
together to form the final synthesiser. Printed circuit designs are
provided for these main modules. Later chapters deal with
sequencing and some effects units.

$11.00

112 pages

MIDI PROJECTS
R. A. Penfold BP0182
Provides practical details of how to interface many popular home
computers with MIDI systems. Also covers interfacing MIDI
equipment to analogue and percussion synthesisers.
$11.00
112 pages

MORE ADVANCED ELECTRONIC MUSIC PROJECTS
R. A. Penfold BP0174
Intended to complement the first book (BP74) by carrying on where
it left off and providing a range of slightly more advanced and
complex projects. Included are popular effects units such as flanger,
phaser, mini-chorus and ring-modulator units. Some useful
percussion synthesisers are also described and together these
provide a comprehensive range of effects including drum, cymbal
and gong-type sounds. ;
8.50

96 pages

COMPUTER MUSIC PROJECTS

R. A. Penfold BP0173
Shows some of the ways a home computer can be used to good
effect in the production of electronic music. Topics covered include
sequencing and contro! via analogue and MIDI Interfaces,
computers as digital delay lines and sound generators for computer

control.
$11.00
112 pages
MISCELLANEOUS
COIL DESIGN AND CONSTRUCTION MANUAL
8. B. Babani BPO160

A complete book for the home constructor on ‘‘how to make” RF,-
IF, audio and power coils, chokes and transformers. Practically every
possible type is discussed and calculations necessary are given
and explained in detail. All mathematical data is simplified for use
by everyone.

$9.50

96 pages

AN INTRODUCTION TO Z80 MACHINE CODE
R. A. & J. W. Penfold BP0152
Takes the reader through the basics of microprocessors and
machine code programming with no previous knowledge of these
being assumed. The microprocessor dealt with is the Z80 which
is used in many popular home computers and simple programming
examples are given for Z80-based machines including the Sinclair
2X-81 and Spectrum, Memotech and the Amstrad CPC 464. Also
applicable to the Amstrad CPC 664 and 6128.

$10.00

144 pages

A 2-80 WORKSHOP MANUAL
E. A. Parr BP0112
This book is intended for people who wish to progress beyond the
stage of BASIC programming to topics such as machine code and
assembly language programming, or need hardware details of a
Z-80 based computer.

$12.00

192 pages

GETTING THE MOST FROM YOUR PRINTER
J. W. Penfold 6P0181
Details how to use all the features provided on most dot-matrix
printers from programs and popular word processor packages like
Wordwise, Visawrite and Quill, etc. Shows exactly what must be
typed in to achieve a given effect.

$11.00

96 pages

CIRCUITS & CONSTRUCTIONAL
PROJECTS

BEGINNERS GUIDE TO BUILDING ELECTRONIC PROJECTS

R. A. Penfold BP0227
Shows the complete beginner how to tackle the practical side of electronics,
80 that he or she can confidently build the electronic projects that are
regularly featured in the popular magazines and books. Also includes
examples in the form of simple projects that you can build.

$8.50
112 pages

_F. G. Rayer

50 PROJECTS USING RELAYS, SCRs AND TRIACs

F BP0037

This book gives tried and practical working circuits which should present

the minimum of dificulty for the enthusiast to construct. In most of the

Circuits there is a wide latitude in component values and types, allowing

@asy modification of circuits or ready adaption of them to individual needs.
$8.50

112 pages

POPULAR ELECTRONIC PROJECTS
R.A. Penfold BP0049
Provides a collection of the most popular types of circuits and projects
covering a very wide range of interests, including Radio, Audio, Household
and Test Equipment projects.
$9.50
144 pages

ELECTRONIC TEST EQUIPMENT CONSTRUCTION

F. G. Rayer BPOO75

This book covers in detail, the construction of a wide range of test

equipment for both the electronics hobbyist and radio amateur. Included

are projects ranging from a FET amplified voltmeter and resistance bridge

to a field-strength indicator and heterodyne frequency meter.

Not only can the home constructor enjoy building the equipment but the

finished product can also be usefully utilised in the furtherance of his hobby.
$8.00

96 pages

HOW TO USE OP-AMPS BP0ss
E. A. Parr
This book has been written as a designer's guide covering
many operational amplifiers, serving both as a source book
of circuits and a reference book for design calculations. The
approach has been made as non-mathematical as possible
and it is hoped, easily understandable by most readers, be
they engineers or hobbyists.

$11.00

160 pages

ELECTRONIC GAMES

R.A. Penfold BPO069
Contains a number of interesting electronic games projects using modern
integrated circuits. The text is divided into two sections, the first dealing
with simple games and the latter dealing with more complex circuits thus
making the book ideal for both beginner and mare advanced enthusiast alike.

$8.00
96 pages
NEW RELEASES!
A TV-DXERS HANDBOOK BP0176

R. Bunney
Completely revised and updated by Roger Bunney who is
probably one of the leading authorities in this country on the
subject. Includes many units and devices which have been
designed and used by active enthusiasts, and often,
considerable ingenuity and thought have gone into the
development of such units to overcome individual problems.
A practical and authoritative reference to this unusual
aspect of electronics. (Large Format) $18.00

AN INTRODUCTION TO CP/M
R. A. Penfold ;

CP/M is more than just a program to give a common set of
standards and hence software compatibility between various
computers. It includes a range of commands that help with
such things as file copying and editing, the directing of data
to the appropriate device etc. In order to get the best from
CP/M and the programs running under it, a basic
understanding of the system is highly desirable, and this book
tells the story. 96 pages $11.00

BP0179

BP0183

ELECTRONIC CIRCUITS FOR

THE COMPUTER CONTROL OF ROBOTS
R. A. Penfold

Provides information and circuits on computer control of
electric motors (including stepper types), plus a range of
useful sensors including visible light, infra-red, and ultrasonic
types. 96 pages $11.00

USING YOUR AMSTRAD CPC DISC DRIVES
J. W. Penfold

Covers such things as tracks, sectors and formatting;
AMDOS and CP/M operating systems including rules and
regulations, filing from BASIC, file copying and transfer;
program development including MERGE and CHAIN
MERGE; CP/M turnkey discs etc.

BP0189

$11.00
96 pages

IC 555 PROJECTS

E. A. Parr BP0044

Every so often a device appears that is so usefull that one wonders how

life went on before without it. The 555 timer is such a device. Included

in this book are basic and general circuits, motorcar and model railway

rouls, alarms and noisemekers as well as a section on the 566, 568 and 559 timers.
$9.50

176 pages (Available February 1987)

HOW TO DESIGN AND MAKE YOUR OWN P.C.B.s
R. A. Pentold BPO121
Chapter 1 deals with the simple methods of copying printed circult board designs
from magazines and books and covers all aspects of simple P.C.B. construction
@8 comprehensively as possible. Chapter 2 covers photographic methods of
Producing p.c.b.s and Chapter 3 deals with most aspects of designing your own
printed circult board layouts.

$6.50

80 pages

POWER SUPPLY PROJECTS
R. A. Penfold BPOO76
The purpose of this book is to give a number of power supply designs,
including simple unstabilised types, fixed-voltage regulated types, and
variable-voltage stabilised designs, the latter being primarily intended for
use as bench supplies for the electronics workshop. The designs provided
are all low-voltage types for semi-conductor circuits. This book should also
help the reader to design his own power supplies.

$7.50

96 pages

HOW TO DESIGN ELECTRONIC PROJECTS
R. A. Penfold BP0127
‘The aim of this book is to help the reader to put together projects from standard
Crcult blocks with a minimum of tial and error, but without resorting to any acvanced
mathematics. Hints on designing circuit blocks to meet your special requirements
where no “stock” design is available are also provided.

$9.00

128 pages

ELECTRONIC SECURITY DEVICES
R. A. Penfold BPOOS6
Many people associate the term ‘‘security device” with only burglar alarms
of various types, but in fact, any piece of equipment which helps to protect
people and property against any form of danger could be termed a
“security device’’.
Therefore this book, besides including both simple and more sophisticated
burglar alarm circuits using light, infra-red and ultrasonics, also includes
many other types of circuits as well, such as gas and smoke detectors,
flood alarms, doorphone and baby alarms, etc.

$9.50

112 pages

FURTHER PRACTICAL ELECTRONICS
CALCULATIONS AND FORMULAE

F. A. Wilson

Written in the same style as the first book (BP53) and with
the same objectives in mind, this book is divided into the

BP0144

nd... Babank Books

COMMUNICATION

(Elements of Electronics — Book 5)

F. A. Wilson BPO00sS
A look at the electronic fundamentals over the whole of the
communication scene. This book aims to teach the important
elements of each branch of the subject.

Most of the modern transmissions system techniques are examined
including line, microwave, submarine, satilite and digital multiplex
systems, radio and telegraphy. To assist in understanding these
more thoroughly, chapters on signal processing, the electromagnetic
wave, networks and transmission assessment are included, finally
a short chapter on optical transmission.

$11.00
256 pages
50 SIMPLE LED
CIRCUITS
R. N. Soar BP0042

Contains 50 interesting and useful circuits and applications, covering
many different branches of electronics, using one of the most
inexpensive and freely available components — the light-emmiting diode
(LED). Also includes circuits for the 707 common anode display.

$6.00
64 pages
IC PROJECTS FOR
BEGINNERS
F. G. Rayer BP0097

Offers a range of simple projects based around a number of popular
and inexpensive linear and digital integrated circuits.

With most projects, complete layout and/or point-to-point wiring
diagrams are included to help simplify construction.

$8.50
112 pages
ELECTRONIC PROJECTS
USING SOLAR CELLS
O. Bishop BP0082

This is a book of simple circuits which have applications in
and around the home and that are designed to be powered
by the energy of the sun. Although, if the reader wishes, they
could alternatively be powered by the ordinary button cells
or small dry batteries.
$8.50
128 pages

following fourteen sections: Electricity, Electrostatics,
Electromagnetism, Complex numbers, Amplifiers, Signal
Generation and Processing, Communication, Statistics,
Reliability, Audio, Radio, Transmission Lines, Digital Logic
and Power Supplies. 512 pages $16.00

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EA JUN '87

Part 5: The colour decoder — 1

Understanding

By far the most complicated part of a modern
colour TV receiver is the colour decoder. Here
we examine how the decoder circuit works
and discuss how the various signals are

derived.

by DAVID BOTTO

In part 3 of this series we saw that
the transmitted TV signal contains: (a)
the monochrome signal carrying the fine
detail of the picture; (b) the colour in-
formation consisting of ‘“U” and PAL
switched ‘‘V” suppressed carrier signals;
(c) the “swinging burst” colour syn-
chronisation signal; (d) the line and
field synchronising pulses needed to
keep the receiver’s raster in step with
the camera scan; and (f) the frequency
modulated sound signal.

Since all the colour information is en-
coded before transmission, it must be

o oe ay
c o cs
21 s
3

decoded after demodulation by the re-
ceiver’s video detector so that these
various signals can be applied to the
correct sections of the receiver.

The colour bar signal

A standard colour bar signal produces
a pattern of vertical bars on the screen
of a colour television receiver. Viewed
from left to right, the bars are white,
yellow, cyan, green, magenta, red and
blue (Fig.1). Notice that yellow, cyan
and magenta are produced by additive
colour mixing.

PEAK WHITE

colour television

This colour bar signal may be trans-
mitted by the TV station or produced
by a colour bar generator and fed into
the receiver antenna socket. When an
oscilloscope is connected to various
points in the colour receiver, the vari-
ous waveforms can be easily identified.
This makes the colour bar signal very
useful in the study (and servicing) of a
colour TV receiver.

Fig.2 shows one line of a mono-
chrome television picture, while Fig.3(a)
shows a complete colour bar waveform
where the signal is at 100% amplitude
and with 100% colour saturation.
Fig.3(b) shows the colour bar signal as
transmitted by the British Broadcasting
Corporation at 100% amplitude and
95% colour saturation. Fig.3(c) is the
colour bar signal as defined by EBU
standards for Europe with 75% ampli-
tude and 100% colour saturation.

Notice how the ten-cycle colour burst
signal sits on the “back porch” of the
line synchronizing pulse.

“BRIGHTNESS”
SIG!

Fig.1 shows the standard colour bar signal as displayed on the TV screen, while Fig.2 shows one line of a monochrome video signal.

112 ELECTRONICS Australia, June 1987

To prevent the colour subcarrier in-
terfering with the luminance signal and
producing objectionable patterning on
the received colour picture, suppressed
carrier modulation is used at the TV
transmitter. The colour information of
the transmitted program is then sent in
the form of sidebands only (see part 3).
Thus, in the colour TV receiver, it is
necessary to replace the missing carrier
so that the original amplitude modu-
lated colour signals can be recovered.

The colour decoder

Fig.4 shows a block diagram of a typi-
cal colour decoder. The decoder cir-
cuitry separates the various parts of the
complete signal and demodulates the
“U” and “V” colour signals. You will
remember that the “U” signal contains
the (B-Y) colour information, and the
“V” signal the (R-Y) information.

In Fig.4, point “A” is where the sig-
nal from the video detector enters the
decoder. If we tuned the TV receiver to
a colour bar transmission, an oscillo-
scope connected to “A” via a 10:1 iso-
lating probe would display the complete
colour bar signal.

From point “A”, the signal travels
through a bandpass filter which removes
the luminance signal, allowing only the
chrominance information and burst sig-
nal to pass. At point “B”, the signal ap-
pears as in Fig.S(a). The following
chrominance amplifier supplies the sig-
nal to a burst blanking circuit, which is
controlled by pulses from the line time-
base circuitry. This removes the “swing-
ing burst” signal so that the signal at
point “C” appears as in Fig.5(b).

Because of the way it looks, this sig-
nal is often referred to as a “cotton
reel” waveform. Two detector circuits
are needed, one to demodulate the “V”
signal while the other demodulates the
“U” signal.

From point “C”’, the signal is fed to
the PAL delay line and to the adder
and subtractor circuits. The output from
the adder circuit is the “U” signal,
while the output from the subtractor is
the ““V” signal.

Fig.6 shows the basics of the PAL
glass delay line. The incoming electronic
signal is first fed to a transducer which
converts it to an ultrasonic wave. This
wave is then detected by a second trans-
ducer and converted back to electronic
form. Because ultrasonic signals take
time to travel through the glass, this
gives rise to a delay time. In a PAL co-
lour TV receiver, the delay line is
manufactured to extremely tight toler-
ances to give a delay time of 63.943 mi-
croseconds.

1V PEAK

YELLOW

MAGENTA

10 CYCLE COLOUR
BURST

LINE SYNC
PULSE

YELLOW

OV BLACK —
1
LINE SYNC
PULSE

1V PEAK
WHITE
LEVEL

YELLOW

OV BLACK — F
LEVEL
is hen
-0.3V — \

LINE SYNC
(c) PULS

10 CYCLE COLOUR
BURST

LINE enns-~|

MAGENTA

0 CYCLE COLOUR
BURST

LINE ENDS ”

MAGENTA

LINE ENDS 7

Fig.3: these diagrams show complete colour bar waveforms for varying amounts of ampli-
tude and colour saturation (see text). Note the 10-cycle colour burst signal on the back

porch of the line sunchronising pulse.

Fig.7(a) shows the delay line and
adder and subtractor circuitry of a typi-
cal commercial colour TV set.

Suppose that two lines of chroma in-
formation arrive at “C” (Fig.4), each
line possessing the same hue and satura-
tion. The first line, which we’ll call F1,
is amplified by transistor Q1 and goes
through the delay line and emerges 64
microseconds later across coil L. This
means that the signals at points x and y
will be of equal voltage but of opposite
phase. The next line of chroma informa-
tion, which we will refer to as F2, ar-
rives directly at point z at exactly the
same time as line F1. Thus, lines Fl and
F2 arrive together at coil L.

At point x on L, the + and — “U”
signals will cancel out and the two —““V”

signals will add together to produce a
signal voltage of -2“‘V” (Fig.7(b)). At
the bottom of coil L, the + and — “V”
signals will cancel out, and the two “U”
signals added to produce a voltage of
+2°U”’,

When the next line of signal arrives
(line F3), line two will have passed
through the delay line, and line F3 will
arrive direct. The result will be as in
Fig.7(c).

The “U” voltages will again cancel
out, and the ‘“‘V” voltages will add to
give +2“V”. At the bottom of coil L,
the ‘““V” voltages will cancel and +2“U”
will be produced. In any two lines, hue
errors will occur in opposite phase di-
rections. Because chroma errors will be
a product of two lines, the errors will

ELECTRONICS Australia, June 1987 113

POINT "A"

DELAY LINE
0.6us

DELAY LINE
64ys

LUMINANCE
AMPLIFIER -

a‘ SUB CARTIER
PHASE
DETECTOR Pile OSCILLATOR

APC LOOP.

7.8kHz
SHAPER
(IDENT)

SUBTRACTOR

aye
DEMODULATOR
90° PHASE
SHIFT
“yn
DEMODULATOR

PAL 180°
SWITCH

LUMINANCE” |
OUTPUT

(FY) R-Y
AMPLIFIER SGT BUT

TO
MATRIX
CIRCUITRY

(8 ¥) B-Y
AMPLIFIER OUTPUT

Fig.4: block diagram of a typical PAL colour decoder. The way in which each block works is explained in the text.

cancel and the correct hue will be pro-
duced.

Similarly, because the ‘‘burst” signal
switches 45 degrees above and below
the -““U” axis every other line (Fig.8),
burst errors due to transmission errors
will tend to cancel. We will see the rea-
son for this when we discuss subcarrier
recovery.

Note that the outputs at the top of
coil L are “V” signals only, and those

(a) WAVEFORM AT “B" Fig. 4

‘LF

at the bottom of coil L “U” signals
only. So the PAL delay line and the
adder and subtractor circuitry have
separated the ‘““U” and ‘“‘V” signals.

VRI in Fig.7(a) adjusts the gain of
transistor Q1. Together with the preset
phase adjustment, this allows compensa-
tion to be made for any delay line and
circuit variations.

The signals at “F’ and “G” in Fig.4
now appear as in Fig.5(d). These “oP

(b) WAVEFORM AT "C”

(d) WAVEFORMS AT “F” AND “G"

i =

(e) WAVEFORM AT “H™ 7.8kHz RIPPLE

(f) WAVEFORM AT “D" 7.8kHz SINE WAVE

Fig.5: these diagrams show the waveforms at various points on Fig.4 (see text).

114

ELECTRONICS Australia, June 1987

and ‘“V” chroma subcarriers, have a 90
degree phase difference between them
and must be separately demodulated.
However, before discussing how this is
done we first need to know how the co-
lour burst signal is used.

.

Separating the burst signal

The output of the chrominance ampli-
fier, consisting of the chroma signal and
the colour burst, is also applied to the
burst gate and amplifier circuitry
(Fig.4). A pulse from the line timebase
circuitry controls (or gates) this ampli-
fier, allowing it to operate only for the
duration of the ten-cycle colour burst
signal.

The amplified burst signal emerges at
“E”. It is then applied to the following
phase detector stage, where it is com-
pared in phase with the TV receiver
4.43MHz subcarrier oscillator.

This 4.43MHz crystal controlled oscil-
lator is used to replace the missing sub-
carrier. While some texts refer to this as
“re-inserting” the carrier, it is more ac-
curate to say that the output generated
by the receiver subcarrier oscillator is
modulated by the “U” and “V” colour
sidebands. The resulting signals are then
demodulated to reproduce the required
colour signals.

As shown in Fig.4, an automatic
phase control (APC) loop signal is fed
back to the phase detector. Fig.10(a)
shows the basic circuit.

The colour burst signal is applied to

connections “1” and “2” of transformer
T. The signals on the secondary winding
at points “3” and “4” are 180 degrees
out of phase with each other. Thus, cur-
rent will flow through the diodes only
during positive half-cycles at position
“3” and negative half-cycles at position
“4”. The output from the local
4.43MHz oscillator is applied to point

You will see from Fig.10(b) that the
local oscillator sine wave output passes
through its zero position at the peaks of
the burst signal. This can only happen
when the phase of the oscillator “lags”
exactly 90 degreees behind the burst sig-
nal. It then follows that, because the
diodes are centre connected anode to
cathode,: there will be no DC output
voltage at “H”.

We know that the colour burst signal
swings 45 degrees above and below the
—“U” axis during every other line of
picture signal (Fig.8). Thus, the “mean”
or average of the phase of the colour
burst ‘signal is on the —“U” axis. The
circuit is so designed that the subcarrier
oscillator responds only to this mean
value.

The subcarrier oscillator is thus
“locked” to the same frequency and
phase as the +‘‘V” chroma signal.
When the local oscillator “lags” behind
the mean of the burst signal by 90 de-
grees there will be no DC voltage out-
put at the wiper of preset resistor R1
(point “H”’), as stated previously. How-
ever,. if the frequency or phase of the
local oscillator changes, the currents
flowing through diodes D1 and D2 will
no longer be equal, and a positive or
negative DC output voltage will be pro-
duced at “H”. This voltage is then ap-
plied to the subcarrier oscillator to cor-
rect its frequency and phase.

The phase detector produces another
useful signal. As the burst signal swings
above and below the —“U” axis, a half
line frequency (7812.5kHz) pulse is pro-
duced. This pulse is amplified and

shaped to synchronise the PAL switch °

(see Figs.4, Se and 5f).

Some early model colour TV receiv-
ers did not contain a 4.43MHz crystal
oscillator. Instead, the colour burst sig-
nal was amplified and used to energise a
“ringing coil” circuit. The resulting
4.43MHz signal was then used instead
of a conventional crystal oscillator, but
the decoder adjustments were quite
critical in such sets.

You'll find that many of the latest
PAL receivers contain subcarrier oscilla-
tors controlled by an 8.867MHz crystal.
This arrangement is becoming increas-
ingly popular with manufacturers. Why

~

=e

T= _

ULTRASONIC
WAVES

Fig.9(a) shows the circuit of a popular

type of synchronous demodulator. The
signal from the TV’s 4.43MHz subcar-
rier oscillator passes through R1 and R2
to points “X” and ““Y”. The values of
the components are selected so that
when ‘‘X”’ approaches its positive peak
and “‘Y” its negative peak, the diodes
conduct. It is only during this period of
time that there is a path for the chromi-
nance signal between point “‘P” and the
output.

In Fig.9(b), the dotted line represents

the waveform of the transmitted signal,
and the solid line as it actually appears
at point “P”. The subcarrier frequency
is of course 4.43MHz, but for simplicity
is shown as just a few cycles.

Fig.9(c) shows the locally generated

subcarrier, the solid portions of the line

LINE F2
DIRECT

DIRECT SIGNAL _—-*

CANCELLED

+

oye
Ut oe a op et"
1
i)
'

CANCELLED, -— +2"U"
NAS

'
=v"

TRANSDUCER: SIGNAL IN

TRANSDUCER: SIGNAL OUT
64ys LATER

Fig.6: basic scheme for a PAL glass delay line. The output signal emerges 64s after the
input signal.

and how the 8.8MHz oscillator is used
will be discussed in a later article.

Demodulating the
“U” and “V” signals

representing the periods when the
diodes conduct. Look carefully at the
diagrams and you will see that, during
period “A”, the positive peaks of the
subcarrier occur at exactly the same
time as the positive peaks of the chroma
signal.

However, during period “B” the
phase of the incoming chroma signal
changes by 180 degrees. Now the nega-
tive peaks of the chroma signal occur at
the same time as the positive peaks of
the local subcarrier. The result is that,
during period “A”, the positive half-
cycles of the chroma signal are demodu-
lated. Similarly, during period “B”’, the
negative half-cycles are demodulated.

Fig.9(d) depicts the resulting output
waveform at ‘‘Q”’. The solid line across
the signal peaks shows the output signal
after filtering by choke L1 and capaci-
tors C1 and C2.

If the local oscillator signal is not in
correct phase with the chroma carrier,
the signal output at “Q” will only be a

“y"

ay ‘ PRESET PHASE
ADJUSTMENT

AT POINT “x” |

ove

AT POINT “2”
+"U"
+"

AT POINT “y”

ean

“Vv" OUTPUT

“U" OUTPUT

Fig.7: the delay line and adder and subtractor circuitry of a PAL colour TV set.
ELECTRONICS Australia, June 1987

115

slight ripple. The filter stage then re-
moves this ripple so there is no output
signal. If, in Fig.9(a), diodes D2 and D3
are replaced by suitable resistors, the
circuit will still work and this configura-
tion is in fact commonly used.

The two synchronous demodulators
used in the colour receiver for demodu-
lation the “U” and “V” signals are usu-
ally identical.

Synchronising the PAL
switch

There is a phase difference of 90 de-
grees between the transmitted “V” and
“U” colour signals. For this reason, the
output from the crystal controlled oscil-
lator is phase shifted by 90 degrees be-
fore it is fed to the ‘““U” synchronous
demodulator (Fig.4).

In addition, a signal is also fed from
the subcarrier oscillator to the ‘‘V” syn-
chronous demodulator via the 180 de-
gree PAL switch. The PAL switch must
be properly synchronised to ensure that
the subcarrier fed to the ‘““V” detector is
correctly “‘in step” with the transmitted
“Vv” signal. You'll remember that the
“Vv” signal is switched 180 degrees
every other line at the TV station.

LOCAL
OSCILLATOR
4.43MHz IN

O
CHROMA IN

[/-#--s—————— PERIOD :
5 ea a —

The PAL switch is operated by the
application of a square wave from what
is called a bistable or “flip-flop” circuit
which has two outputs. A square wave
appears at each output in turn every
time a switching pulse arrives from the
receiver line circuity. A “triggering”
pulse is required to ensure that the bist-
able circuit correctly synchronises the
receiver PAL switch. é

Without this triggering pulse the bist-
able circuit would still work. However,
if the PAL switch is not correctly ‘‘in
step” with the switched ““V” signal as
received from the TV station, incorrect
colours appear in the picture. For exam-
ple, if you look at the relative phase
angle diagram shown in part 2 of this
series, you will see that green colours
would show as red.

You will see from Fig.4 that the
7.8kHz (7.8125kHz) half line frequency
ripple pulse produced in the phase de-
tector is applied to a 7.8kHz shaper cir-
cuit. Here it amplified and shaped so
that a 7.8kHz sine wave signal is pro-
duced. This signal synchronises the bist-
able circuit, ensuring that the TV re-
ceiver PAL switch is correctly in phase
with the transmitted “V+” and ‘“‘V-” on
each line of the chroma signal. Because

SIGNAL OUT

(a)

weed ar PERIOD "B"

CHANGES HERE

SIGNAL PHASE ———"|

Fig.9: circuit diagram for a popular type of synchronous demodulator.

116 ELECTRONICS Australia, June 1987

LINE F1

LINE F2

Fig.8: the colour burst signal swings 45 de-
grees above and below the —‘‘U’’ axis on
alternate lines.

the 7.8kHz sine wave correctly identifies
these lines, it is referred to as the
“ident” signal.

The 7.8kHz ident signal is also used
to control the colour killer circuitry. As
you can see from Fig.2, during a mono-
chrome transmission the colour burst
signal is not transmitted. This means

‘ that the burst signal, the 7.8kHz pulse

from the phase detector, and therefore
the ident signal will not be produced.

The result is that the signal from the
colour killer to the chrominance ampli-
fier is absent and thus the chrominance
amplifier is biased off. The reason for
doing this is very simple — if the
chrominance amplifier continued to
work during a black and white transmis-
sion, colour patterns and splashes would
be visible on the picture.

The ACC (automatic colour control)
signal from the burst gate and amplifier
is fed back to the chrominance ampli-
fier. The voltage of this signal depends
on the amplitude of the received colour
burst and controls the gain of the
chrominance amplifier. This keeps the
level of the colour saturation of the pic-
ture constant if the received signal
should vary in strength.

When the PAL switch is correctly
synchronised to the signal, the local
4.43MHz carrier will be in the correct
phase and frequency to be fed to the
“V” demodulator. As stated above, the
90-degree phase shifted oscillator signal
is fed to the ““U” demodulator. Follow-
ing demodulation, the resulting (R-Y)
and(B-Y) signals are amplified and fed
to the matrix circuitry.

The NTSC decoder

An NTSC colour transmission, as
you'll recall, uses “I”? and ‘“‘Q”’ signals
instead of “WV” and “U” signals. The
“T” signal is 33 degrees from the PAL
“V” signal and the ‘‘Q” signal 33 de-
grees from the “U” signal (see part 2 in
this series). The “I” signal is not
switched every other line as is the ‘“V”
signal. A block diagram of an NTSC

decoder resembles Fig.4 but the bistable
and PAL switch circuitry would be ab-
sent.

The signal from the TV receiver’s
subcarrier oscillator (3.579545MHz for
the USA) is sent directly to the “I”
demodulator which replaces the “V”
demodulator in our block diagram.

PAL-S and PAL-D

Some early PAL colour TV receivers
used Pal-S circuitry. In a PAL-S (PAL-
Simple) receiver, the PAL delay line
and adder and subtractor circuitry is
omitted. In any two lines, hue errors of
the same colour occur in opposite phase
directions. When this happens, the
PAL-S receiver relies on the eye to
average out any differences in hue.

However, if there are large colour
phase errors between two close lines of
picture, bar patterns, known as “Han-
over”’ blinds, will appear on the picture.
To overcome this problem, a phase con-
trol was fitted between the subcarrier
oscillator and the two synchronous
demodulators. The viewer then adjusted
this control for maximum reduction of
the blind effect.

The PAL-D (PAL-deluxe or PAL-
delay) decoder, as shown in Fig.4, thus

RADIO/TELEPHONE SIMPLEX INTERCONNECT

on SMARTPATCH MODEL 5700

AUDIO CC

4

“qn

INPUT FROM
“SWINGING BURST”
SIGNAL

“gn

Fig.10: typical phase detector circuit.

displays a superior colour picture when
compared to the simpler PAL-S receiv-
er. For this reason, all modern sets use
PAL-D colour decoders. In fact, in the
very latest designs, most of the decoder
circuitry is taken care of by a. single
large scale integrated circuit.

INPUT FROM LOCAL
4.43MHZ OSCILLATOR

LOCAL OSCILLATOR
<— SIGNAL

In part 6, we’ll examine the lumi-
nance signal and describe how the sig-
nals are combined in the matrix circuit-
ry. We’ll also take a look at the signals
passing through the colour difference
amplifiers and discuss how the G-Y sig-
nal is recovered. ®@

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ELECTRONICS Australia, June 1987 117

Tandy’s new 1000SX personal computer

Tandy has announced the release of
their new business oriented computer,
the 1000SX.

The Tandy 1000SX features an Intel
8088 microprocessor which has a clock
speed of 7.16 or 4.77MHz. It has five
user-accessible IBM PC compatible card
slots, raising the 1000SX’s standard
RAM complement of 384K to 640K.

1.1GHz frequency counter

Philips has released the PM6669 fre-
quency counter. The unit incorporates a
MTCXO (mathematically temperature-
compensated crystal oscillator), making
the PM6669 a low-cost instrument.

In the MTCXO principle, the time-
base crystal oscillator is individually
calibrated by factory measurement of its
temperature vs. frequency curve, which
is then permanently stored in a non-
volatile memory. The correction factor

118 ELECTRONICS Australia, June 1987

To complement the new PC, Tandy
has included an improved edition of the
Deskmate Software. Deskmate II fea-
tures six applications on one disk, and it
also allows the user to exit Deskmate II
to enter a program and then easily re-
turn to Deskmate.

For further information contact your
local Tandy Electronics store.

from Philips

for any temperature is then automati-
cally applied to the measurement before
it is displayed.

Other features of the PM6669 are: a
full 9-digit display, a measuring range
from 0.1Hz up to 120MHz (optionally
up to 1.1GHz), high-sensitivity wide-
band input circuitry with automatic,
error-free triggering on all input wave-
forms, continuously variable attenua-
tion, and a switchable low-pass filter for

Mobile telephone
from Philips

Philips has developed a new cellular
radio telephone for use with Telecom’s
MobileNet system.

Called the “Traveller”, the new
phone will work with telephone systems
in the US and Canada as well as those
in Australia and New Zealand, thus
opening up potential export opportuni-
ties for Australia.

The unit is being built at the Philips
Clayton plant and incorporates ad-
vanced surface mount and large scale
integration components.

Telecom has exclusive Australian
rights for the ‘Traveller’. However,
Philips also plans to release a new radio
of a similar type to be sold directly by
Philips in Australia and overseas.

For further information contact
Philips, 15 Blue St, North Sydney, NSW
2060. Phone (02) 925 3333.

noise suppression.

For further information contact
Philips Scientific and Industrial, 25-27
Paul St, North Ryde, NSW 2133.

Icom’s new
M-700 marine
transceiver

Icom has released a new addition to
their marine transceiver range.

The M-700 is a 48- channel high fre-
quency SSB/AM marine transceiver
which is able to transmit and receive on
any authorised marine channel from 2
to 23MHz with up to 150 watts output.

Allocation of frequencies to the 48
simplex and semi-duplex memory chan-
nels can be made according to individ-
ual requirements.

Frequency selection is controlled by

two rotary channel switches. The first
controls channel group selection, with
three channel groups (A, B and C) in
logical order according to purpose and a
fourth position providing instant emer-
gency access to the 2182kHz Interna-
tional Safety and Calling Frequency.
The second controls selection of 16 fre-
quencies within each logical channel
group.

The M-700 is fitted with a signal
“clarifier” to adjust the pitch of re-
ceived SSB signals, making off-fre-
quency signals easier to understand.

For further information contact Icom
Australia, 7 Duke Street, Windsor, Vic.
3181. Phone (03) 529 7582.

Hewlett-Packard has released the new
Versatile Link fibre-optic components
which are designed to be used in plastic
fibre-optic applications.

Three categories of performance are
offered: standard at 1Mbd up to 5
metres; high performance at 1Mbd up
to 40 metres; and high performance at
5Mbd up to 25 metres.

HP’s new link fibre-optic components

The new link features a choice of

package, connector, cable and optoelec-

tronic performance. The three types of

connectors offered include:
simplex latching and duplex.

For further information contact VSI
Electronics (Australia) Pty Ltd, 16
Dickson Avenue, Artarmon, NSW
2064. Phone (02) 439 4655.

simplex,

Compact lab supply
from Amtex

Amtex Electronics has released the
MS-200 four output laboratory power
supply.

The MS-200 is modular and allows
the customer to select any four modules
to suit their requirements from the fol-
lowing voltage ranges: 4.4 to 5.6V at 5
to 10A output; 11 to 17V at 2 to 3.5A;
21 to 28V at 1 to 2A; and 42 to 55V at
0.5 to 1A.

The unit has red LED readouts for
voltage indication and green readouts
for current indication. Maximum output
voltage ripple is S0mV p-p and load
regulation is within 1%.

For further information contact
Amtex Electronics, 36 Lisbon Street,
Fairfield, NSW 2165. Phone (02) 727
5444,

IBM PC
compatible motherboard

For those needing a new motherboard
for their IBM PC, Electronic Solutions
is now selling a high-quality 1OMHz no-
wait-state motherboard.

The board is a direct drop-in replace-
ment for the IBM PC board but runs at
around four times the speed. It has
complete IBM compatibility, uses a
8088-1 processor and comes complete
with 640K of memory, using the latest
high speed 41256 chips.

For further information contact Elec-
tronic Solutions, PO Box 426, Glades-
ville NSW, 2111. Phone (02) 427 4422.

66 55 Compilers for

Single-chip
micros

“C” Cross compilers for PC/XT/AT
and VAX hosts by IAR for:

* 8051 * 68HCII
* 6301/6801/6803 * 64180
FEATURES:

* ANSI “C” standard

* IEEE 32 bit floating point

* Trig. exp. and log. functions

* Easy interface to assembler

* Produces compact, romable code

Package includes compiler,

assembler, universal linker,
librarian and run-time library.

MACRO DYNAMICS:

The Development System Specialists

80 Lewis Rd., Wantirna South 3153.

Tel: (03) 220 7260 Fax: (03) 220 7263

ELECTRONICS Australia, June 1987 119

New Products...

Portable microwave
spectrum analysers

Hewlett-Packard has announced the
release of two new portable, program-
mable microwave spectrum analysers for

Non-contact
measuring system

Ultrasonic Arrays has released a new
ultrasonic distance measuring system,
the DMS-1000.

The new unit measures distance, posi-
tion and thickness to an accuracy of
+0.001 inches. Measurements can be
obtained from most materials, solid,
soft or liquid.

Included in the system is a 33mm ul-
trasonic transducer connected by cable
to a microprocessor based system con-
troller in a NEMA 13 enclosure.

The DMS-1000 can be used as a stan-
dalone gauging system or in a closed-
loop process control system. The con-
troller comes standard with RS-232, 422
and 16-bit parallel outputs for interfac-
ing to host computers, programmable
controllers, recorders, printers or other
system components.

For further information contact El-
measco, 15 McDonald St, Mortlake,
NSW 2137. Phone (02) 736 2888.

New digital
oscilloscope
from Tektronix

Tektronix has announced the release
of their new model 2430A digital oscil-
loscope which is claimed to be much
easier to set up for complex measure-
ments.

The 2340A’s new built-in interface
greatly expands the scope’s capabilities.
Features included are Auto Setup which
sets up the scope for unknown signals;
Waveform Parameter Extraction which
allows the user to select and make com-
plex measurements with the push of a
button; AutoStep which builds, stores
and runs test procedures; and Save on
Delta which checks signals against user
defined limits.

For further information contact Tek-
tronix Australia Pty Ltd, 80 Waterloo
Rd, North Ryde, NSW 2113. Phone
(02) 888 7066.

120 ELECTRONICS Australia, June 1987

laboratory, field and _ production-line
use.

Features of the HP 8562A and 8562B
spectrum analyzers include meeting
MIL-T-28800C, Type III, Class 3,
Style C requirements for ruggedness;
five-minute warm-up time; synthesized
tuning; AM/FM demodulators and

speaker; continuously self-adjusting IF
section; and a plug-in test and adjust-
ment module that speeds trouble-shoot-

ing and adjustments.

The new units are suitable for appli-
cations such as the manufacture and
maintenance of terrestrial and satellite
microwave links, radar systems, telecom
equipment, CATV and LAN systems,
mobile and cellular radios, AM/FM/TV
broadcast equipment and avionics.

For further information contact Hew-
lett-Packard Australia Limited, PO Box
221, Blackburn, Vic. 3120.

Pulsar’s new PC XT/AT compatible motherboards

Pulsar Electronics has released two
PC-compatible motherboards. The
PC/XT and PC/AT motherboards have
high on-board functionality and flexibil-
ity. Both have been designed for low
power consumption and high speed
operation, and to eliminate the need for
additional function cards.

Each motherboard has EGA Mono-
chrome text and graphics, Hercules,
CGA, EGA and Plantronics video
standards on board, software selectable
between modes, auto-detection of con-
nected monitor types, 256K-bytes Dual
Port Graphics RAM on board, and
flicker-free scrolling in all modes.

Also featured are twin RS232 ports,
one parallel Centronics port, one floppy
controller port capable of reading disk
formats from 360K to 2M-bytes, a

games port for dual joy sticks and a
keyboard port.

The Pulsar PC/AT has an Intel 80286
processor running at software selectable
speeds of 1OMHz or SMHz, and 1M-
byte of 100ns dynamic RAM on board
with no wait states. A socket is pro-
vided for a 1OMHz 80287 maths co-pro-
cessor.

The Pulsar PC/XT has an Intel 8088-1
processor, with software selectable
speeds of 4.77MHz, 7.1SMHz and
9.45MHz and a socket for the 10MHz
8087-1 co-processor. On board memory
is 786K of dynamic RAM (100ns) with
no-wait states.

For further information contact Pulsar
Electronics, Lot 21 Catalina Drive, Tul-
lamarine, Vic. 3043. Phone (03) 330
2555.

Programmers

o

EP232
@ The EP232 has proved itself to be a
reliable low cost programmer. It
combines simplicity of use with the
convenience of a self contained RS232
device.

FLEXEPROM
@ A versatile new programmer able to
program just about any EPROM,

CMOS EPROM or EEPROM as well as
single chip micros. No personality
plugs are required; device pin details
and programming parameters are
contained in a user editable
configuration file.

¢ Intelligent & Normal
Programming

@ Intelligent Identifier

@ Easy to use menu driven S/W

@ Screen based editor

Standard RS232 interface

| pam

TTL PROM ADAPTERS
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to program a wide range of TTL
PROMS.

ALL AUSTRALIAN
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Call for details (03) 714 8269
P.O. Box 105, Hurstbridge 3099

ELECTRONICS Australia, June 1987 121

New Products...

New recombination
electrolyte battery

Pacific Dunlop’s Industrial Divison
has released a new Australian-made
battery which uses recombination elec-
trolyte (RE) technology to provide low
cost standby power in industrial sys-
tems.

The Exide Safeguard suits float/re-
charge applications, including emer-
gency lighting, alarm and security sys-
tems, switchgear control, uninterrupt-
able power supplies, standby engine/-
generator starting and communications.

By using the RE principle, Pacific
Dunlop has been able to produce a bat-
tery which is light in weight and offers a
low watt-hour cost. Oxygen generated
in recharging is immediately recombined
internally, eliminating gassing or any
other form of emission or exudation.

The design allows the battery casing
to be sealed completely against interfer-
ence, pollution and the risk of explosion
from external ignition.

The Exide Safeguard units are ini-
tially available in the 2-Volt Model
2v220 and the range will soon also in-
clude the 12-Volt Model 12v38.

For further information contact Pa-
cific Dunlop Industrial Divison, 55
Bryant Street, Padstow, NSW 2211.
Phone (02) 774 0500.

Comair Rotron
announces
new brushless fan

Comair Rotron have introduced a
new brushless DC fan technology: Ther-
maPro-V. This incorporates voltage
regulated circuitry which allows internal
adjustment of fan performance. Many
components on the fan’s printed circuit
board have been replaced with a custom
bipolar chip, enabling a second chip to
be added which offers three new control
capabilities: Thermal Speed Control,
Programmability and Voltage Regula-
tion.

The Thermal speed control is de-
signed to control fan airflow as a func-
tion of temperature. It maintains re-
quired cooling levels, while keeping

Low-cost FET driver from Theta

Theta-J Corporation has released the
FDA200, a new optically-isolated MOS-
FET driver.

The FDA200 incorporates a proprie-
tary photovoltaic integrated circuit ena-
bling it to convert a TTL or CMOS
level current input into a 12 or 14 volt
output to drive discrete MOSFETs.

The FDA200’s two optically-isolated

outputs may be used in series, in paral-
lel, or independently to drive MOS-
FETs for DC or AC loads. The unit op-
erates from —40°C to +85°C and comes
in a standard 8-pin DIP package.

For further information contact Rifa
Pty Ltd, 202 Bell St, Preston, Vic. 3072.
Phone (03) 480 1211.

noise and power consumption to a mini-
mum.

The programmable voltage regulator
allows a single fan to be customised to
meet different airflow applications. The
fan can be designed for minimum air-
flow performance while remaining

within the regulated voltage range. If
airflow and performance remain con-
stant, noise and power consumption will
be minimised.

For further information, contact Total
Electronics, 9 Harker Street, Burwood,
Vic. 3125. Phone (03) 288 4044.

GET THE PICTURE

122 ELECTRONICS Australia, June 1987

FOR THE RIGHT SATELLITE

TV EQUIPMENT AT THE RIGHT PRICE... ;
Dial VIDEOSAT’S TOLL FREE NUMBER C

(008) 22-6865

@ VIDEOSAT

83 Alexandria Parade (Postal: P.O. Box 427)
Wahroonga, NSW, 2076
Telephone: (02) 489 5474

Dealers in all
areas

Trade Enquiries
welcome

New soldering iron from Weller

Cooper Tools has released the Weller
SP30 portable 12 Volt soldering iron
rated at 30 Watts.

The new iron is supplied with non-
polarised battery clips and a 4.5 metre
long lead, allowing use some distance
from the battery power source.

A range of 4mm wide tips is avail-
able, in ‘cone, screwdriver, chisel and
spade types.

For further information contact
Cooper Tools Pty Ltd, PO Box 366, Al-
bury, NSW 2640. Phone (060) 21 5511.

Long life
aluminium
electrolytic capacitors

Elna Co. Ltd has begun production of
the RKA series of Telecom/Commercial
aluminium electrolytic capacitors. The
main feature of the new capacitors is
their minimum guaranteed life span of
4,000 hours at 130°C or 20 years at
ys OF

A major factor in the longer life span
of the new series is the use of a new
electrolyte fluid which is highly stable at
very high temperatures.

Other features include a static capaci-
tance of 2.2uF to 2,200uF; voltage rat-
ing of 10V to 250V; and operating tem-
perature range of minus 55°C to 130°C.

The main applications for the RKA
Series are expected to be in telecom-
munications, automotive and test equip-
ment, and in switchmode power sup-
plies.

For further information contact Soa-
nar Pty Ltd, 32 Lexton Road, Box Hill,
Vic. 3128. Phone (03) 895 0222.

New operational
amplifier from
Precision Monolithics

Precision Monolithics Inc has an-
nounced the release of the OP-42; a
new high-speed, fast-settling precision
operational amplifier. The OP-42 fea-
tures unity-gain stability and a minimum
symmetrical slew-rate of SOV/us. Its
gain-bandwidth product is typically
10MHz and it offers a guaranteed set-
tling-time of lus to 0.01%.

The new op amp has a minumum
open-loop gain of 500,000 into a 10kO
load. Common-mode rejection is 88dB
minmum and it has a low offset voltage
of 750nV.

The OP-42 is available in an 8-lead
TO-99 metal can or ceramic mini-dip,
or in a 20-lead ceramic leadless chip-
carrier for operation over the military
and industrial temperature ranges.

For further information contact VSI
Electronics (Australia) Pty Ltd, 16
Dickson Avenue, Artarmon, NSW
2064. Phone (02) 439 4655.

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Budapest Philharmonic Orchestra (Nos.
1 & 3)

Hungarian State Concert Orchestra (No.
2)

Hungarian Radio Choir (No.3)

Hary Janos Suite; Concerto; Summer
Evening. Sefel Records SE-CD5515.
Playing time: 58 min 26 sec

PERFORMANCE
EE a
» [SAE aT)
SOUND QUALITY
i 2. 3 4 5 6 7 FR H to

Hary Janos is a Hungarian national
folk hero who has been universally lio-
nised. Even his costume has become
part of the Hungarian national heritage.
He is featured in carvings, ceramics,
metals and souvenir plates, and his ex-

- ploits are familiar to every Hungarian.

Thus it might be expected that this
Hungarian performance of Kodaly’s
opera entitled “Hary Janos Suite”
would be sung with gusto and affection.

The opening overture section is not
the usual collection of themes but possi-
bly the composer’s way of showing
sober reality as a contrast to the highly
heroic dreams which follow.

Many people here will be familiar
with parts of this music, such as the

Viennese musical clock but it is all quite
exciting music, modern (composed in
1926), colourful and a contrast to the
baroque and romantic music I am al-
ways raving about.

The second work on this disc, the
Concerto, was written in 1939 for the
50th anniversary of the Chicago Sym-
phony Orchestra. It is a charming one
movement work. The third and_ last
work, Summer Evening, is an idyllic
piece for a chamber orchestra.

The sound on this disc is somewhat
subdued at times yet overall very good.
It is miked a little further away than say
Decca and at times there is slight back-
ground hiss. The balance is fine but not
spectacular. For best results this disc
should not be played too loud as it is
not recorded front row, rather one third

back. Hence a slightly lower sound level
is more natural. On the whole, I can
recommend this disc for its superb per-
formance and fine overall sound.
(RL)

Water Music —
HANDEL

Academy of St. Martin-in-the-Fields
Sir Neville Marriner

Philips 416 447-2 ADD

Playing time: 52 min 16 sec

PERFORMANCE
3 4 § 6 7 38 O WW

SOUND QUALITY
a4 S 6 7 38 9 10

Written in the summer of 1717 for a
Royal party on the river Thames, the
Water Music was an immediate success
which was reported in the “Daily Cour-
ant” some two days later.

There are three suites and this disc
contains all of them in their complete
form. They have striking orchestration
and the main body of strings is comple-
mented by a large and varied wind sec-
tion with frequent use of oboes and bas-
soons. Trumpets are added with french
horns in the D & F suites. In addition,
there are some very colourful move-
ments featuring recorders to great ef-
fect.

The playing by the Academy here
could be described as very crisp with a

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124 ELECTRONICS Australia, June 1987

strong bass and harpsichord line. Yet, I
felt the strings could have played better;
they were not quite up to their usual
stunning standard. However, the
breadth of detail in the music is quite
absorbing and is most enjoyable.

Though I prefer other performances
of these suites, the end result here is
still extremely good even though I feel
the recording itself could be better.

This is just my personal preference to
some of the Academy’s earlier record-
ings which I feel were better miked.
This analog version was made in 1979
and has a slightly different sound with
improved bass and harpsichord but
tends overall to be a bit two channel
mono. (R.L.C.)

Mozart Serenade KV361

Gran Partita

Acadmey of St. Martin-in-the-Fields
Sir Neville Marriner

Philips 412 726-2 DDD

Playing time: 48 min 59 sec

PERFORMANCE
12

SOUND QUALITY
i 2. 3

The serenade for twelve wind instru-
ments and double bass is probably Mo-
zart’s crowning achievement for open-
air wind music (no pun intended). It has
no successor in instrumentation, form,
or sheer brilliance. It is scored for
paired oboes, clarinets, basset horns
and bassoons, plus four horns and dou-
ble bass.

It was begun in 1781 when Mozart
was in Munich for the production of
“Idomeneo”’. It was probably completed
after his return to Salzburg or even
later.

There is a glorious blend of wonder-:

ful woodwind and brass sound to this
work which is almost awe-inspiring,
particularly when performed as it is
here by the ‘‘Academy” which give it a

very coherent and almost heavenly qual-
ity.

Fortunately, as usual with Philips and
the “Academy”, the technical quality
matches that of the performers. The

sound is spectacular, spot on, and front

row seat. But remember, this is still
chamber music (though slightly en-
larged) and this disc should be played
so as not to sound amplified.

‘I hope Philips have good stocks of
this one as I would regard it as standard
reportoire for musicians and hifi buffs
alike. (R.L.C.)

Brahms — Symphony
‘ No.1

Chicago Symphony Orchestra
Sir George Solti

Decca 414 458-2 AAD
Playing time: 48 min 58 sec

PERFORMANCE
ft 2

3 4 5 6 7 8 9
PRT TERT fT Wi]
SOUND QUALITY
2 3 4 5 € 7 _ 8
aS 5,

Completed when Brahms was 43, the
first symphony of this great composer
was some 20 years in preparation. This
was probably due to the formidable
shadow of Beethoven looming over
him.

There are many complex parts to this
music with quite dynamic rhythms and
tuneful melodies creating a brilliant
grandiose effect. The finale of the 4th
movement can leave you with a strong
feeling of “well-being”. It is inspiring
music.

Perhaps though, if you are just enter-
ing the world of classical music, you will
enjoy this music “‘after’”’ Beethoven and
even then you may have to listen to it
two or three times to appreciate the
feeling and depth of this great compos-
ers music.

The performance is right up to the
mark with even minor (as in small!)
woodwind solos played with deep feel-
ing and virtuosity sometimes lacking in
other performances.

Soundwise it is big, right from the
beginning with the strings and tympani.
This is loud third row seat sound and
should be enjoyed this way. Balance is
excellent, though with a slight harshness
to the strings at times — but this is not
a problem.

Overall, I have not heard a better
recording of this work. It is an analog
recording (who cares) which at times
borders on the spectacular. Highly
recommended, but not if you are just
tip-toeing into the world of classical
music. (R.L.C.)

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Problem with
AM/FM stereo tuner

I am writing to request information
on the operating conditions for the AM
local oscillator in the AM/FM stereo
tuner described in December 1985 to
March 1986.

I achieved an acceptable performance
from the oscillator by reducing VR1 to
give a reading of about 0.6V on the
emitter of Q4. At this setting, VRI is
about 50Q and the emitter current
about 12mA. This value of emitter cur-
rent is much greater than the 1-3mA
used in most AM oscillator circuits I
have seen. It concerns me that the oscil-
lator is not operating in the way intend-
ed.

Consider the operating conditions
with VRI adjusted to give the recom-
mended reading of 1.6V on the emitter
of Q4. The base of Q4 will be at about
2.1V (allowing for some conversion of
signal to bias at the base-emitter junc-
tion) and the top of the biasing poten-
tial divider at about 5.1V (assuming the
base current to be negligible in compari-
son with the current through the divid-
er). The current through the 560Q
decoupling resistor will be 12.3mA and

the collector/emitter current about
11.7mA. Thus, VRI1 will be about
1400.

This analysis seems to confirm the
high emitter current, but why is VR1
specified as a 4.7kQ trimpot when a
470Q, unit (say) would greatly facilitate
adjustment? Alternatively, if VRI is
presumed to be about 2k© (half setting)
when adjusted to give 1.6V at the emit-
ter of Q4, then the emitter current will
be about ImA, but the supply voltage
would have to be about 6V to give the
correct bias conditions.

Could you please provide the design
operating conditions for the AM oscilla-
tor; in particular, the emitter current
(which determines the collector voltage
and influences the signal amplitude) and
the signal voltage at the secondary of
the oscillator coil?

To investigate the problem further I
cobbled together an oscillator on a
scrap of Veroboard. This used a coil
wound on a plastic former with the
number of turns for all windings scaled

126 ELECTRONICS Australia, June 1987

Information centre

up (by a factor of about 1.5) to account
for the lower permeability of the coil
former, fixed capacitors for tuning
rather than a varicap, and a BF185 tran-
sistor which I had in the junk box.

This transistor had an h,, of 90 (mea-
sured on a DMM) compared to 85
which I measured for the BF494 in my
tuner. Despite the different compo-
nents, the two oscillators performed in
virtually identical fashion. In particular,
both delivered too much output (about
12V p-p at the secondary of the oscilla-
tor coil) with VR1 set for a reading of
1.6V at the emitter of Q4, and both dis-
played a tendency to ‘‘squegging” when
VRI was increased beyond about 2500.
When the transistor was replaced by a
lower gain type (BF167 with hy. = 47)
the output was reduced significantly and
the tendency to “squegging” virtually
eliminated.

At about the same time, I noticed in

the photographs of the prototype
AM/FM tuner that the oscillator transis-
tor has a metal can encapsulation, while
the BF494 has a plastic encapsulation.
What transistor type was used in the
prototype? My own observations sug-
gest that the oscillator works far better
with low gain transistors. (J.S.T., Eler-
more Vale, NSW).
@ The Q4 transistor used in the proto-
type was a BF115. However, the recom-
mended BF494 was also tested in the
circuit.

A 4.7kQ, trimpot was used for VR1
since it allows a greater range of adjust-
ment for minimum noise of the AM
tuner. After testing a completed tuner
kit we found that the voltage across
VRI could be set to 3.2V with VRI at
about 1.5kQ. On that particular tuner
this gave minimum noise.

The signal voltage for the oscillator is
the maximum that will give the total
AM frequency range as detailed in the
alignment procedure. A greater signal
level will restrict the local oscillator low
frequency range while a smaller signal
will give more noise for AM reception.

Tunable
whip antenna

I have invested considerable time and
money in construction the tunable whip
project described in Electronics Austra-

lia July 1986, but have run into serious
problems with its operation. The unit
performed well enough on the short-
wave bands from 1.5 to 30MHz, and
when linked with my FRG-7 receiver.
However, when tuned to broadcast
band frequencies I get nothing except
background noise.

So I went to work at the bench with
multimeter, RF oscillators and oscillo-
scope. To cut a long story short, I can-
not transfer signals in the 0.5 —
1.5MHz range from the whip “input” to
the DC side of C3, using either current
or voltage feed (they don’t even get to
the DC side of C1). Furthermore, the
performance over the higher SW fre-
quencies bears no relation to what
would be expected from the graphs in
Fig.2, page 52.

I have checked the varicaps, the in-
ductances etc and duplicated the whole.
thing on breadboard to facilitate trou-
ble-shooting — all without success.

Could you therefore help me on what
to look for at various points throughout
the masthead circuitry, or alternatively
put me in touch with the author of the
article for further assistance. (R.D.F.,
Forest Hill, Vic).

@ As far as your broadcast band recep-
tion is concerned, all we can suggest is
that you check the L1 winding and the
type of ferrite or iron powder core
used,

We have sent the letter on to the au-
thor hoping that he may have further
suggestions.

Metric clock
oversight

Having read your April 1987 issue,
my attention was drawn to A. Lay-
about’s design for a Metric Clock. How-
ever, I believe I have found a fallacy in
his circuit description: surely, if the
length of a metric second is only 0.864
olde seconds, and a ‘Hertz’ is defined
as one “‘cycle per second”, then the
metric mains frequency (assuming that
the energy authorities are not about to
change their power systems) will now be
known as 43.2Hz.

I hope A. Layabout is able to re-
spond to this letter before April Ist next
year. (C.W., Applecross, WA).

@ Unfortunately, you have uncovered a

serious oversight in the preparation of
the article on Metric Time and the peo-
ple responsible for preparing this article
have been severely reprimanded. In
fact, the Metric second requires a new
unit for frequency. Instead of Hertz
which relates to the olde second, we
propose the new unit of frequency as
Herring, abbreviated to Hr. The mains
power frequency would then be 43.2
Herrings. Understand?

Herring has a German ring to it, so it
provides some continuity with Hertz.
Herring also has the possibility of co-
lour being applied to it. For example,
you could have blue Herrings to de-
scribe events which occur with depress-
ing regularity and red Herrings for
events which don’t need to be mea-
sured.

Parking lights reminder

false triggers

I built the parking lights reminder
project described in Electronics Austra-
lia July 1986 and installed it in the car,
a current model Ford Laser.

All worked as specified until I turned
on the ventilating fan. The reminder
made slight scratching noises rather like
a mouse under the dash. Then, when
the turning indicators were used, the
noise was a bit more pronounced. Then
when the rear window wiper was used,
it made half hearted chiming noises.

Finally, when the air conditioner,
which has a fan, was turned on, it al-
most made the full chime sound. The
air conditioner cycles on and off about
every two minutes so the chimes were
going most of the time.

When you stop the engine with the
air conditioner going, the chimes do not
sound because they have already gone
through the chime cycle and stopped.

Have you had any other complaints

of the same sort and do you know the
cause of the problem and how to fix it?
(R.G., Croydon, Vic).
@ The problem you have described is
probably due to large voltage spikes on
the supply lines switching transistor Q1
on and thus providing power to the re-
maining circuit.

Depending on where these voltage
spikes are coming from, there are two
possible solutions. If there are positive
spikes on the line from the headlight
switch, the solution would be to connect
a 10Q resistor in series with the line.
Together with the 100uF input capaci-
tor, this will act as a short time-constant
filter.

Alternatively, if there are negative
voltage spikes on the tine from the igni-

tion switch, the solution would be to by-
pass the 1kQ resistor associated with
D1 and D2 with a 104F 16VW electro-
lytic capacitor.

Steering for a
remote control car

I am in the process of making a re-
mote control car out of a lawn mower
motor. I have a problem though. I need
something stronger than a servo to steer
it, as it will be quite heavy when it is
finished. My idea is to somehow take
the wires going to the servo motor and
re-route them to a bigger motor; eg. a
windscreen wiper motor.

One problem is that the motor draws
a lot of current from the servo, so I
need to amplify the current. Another
problem is that the polarity changes.
For example, right turn has two polarity
changes: (1) from centre to right, and
(2) from right back to centre. The same
situation applies for left hand turns.

I hope you understand and can help
me out. (D.D., Deer Park, Vic).

@ We understand your problem al-
though we are not able to offer a ready
solution. We suggest you refer to the
article entitled “Cruise Control for
Cars” published in the June 1984 issue
of Electronics Australia. This used a
servo amplifier to drive a wiper: motor,
so it may be of use in your application.

Remote control
for gates

I am converting our front gates to re-
mote control, using a pair of 12V
motors to operate them.

However, I have been unable to get a
suitable control unit. I need a transmit-
ter with a range of about 35m and the
ability to provide for forward and re-
verse operation of the motors.

One of the staff of the Dick Smith
shop in Brisbane suggested that you
might have a design which would be
suitable. I note that in the April issue of
Electronics Australia you refer to a re-
mote control switch described in the
January issue. I have not seen this arti-
cle but assume it is only for on-off
switching — not reversible.

Alternatively you may be able to sug-
gest possible suppliers of suitable made-
up units or kits. (R.D.J., Newrybar,
NSW).
® According to the designer of the
UHF remote switch described in the
January 1987 issue of EA, the transmit-
ter has a range of up to 50 metres in
open space. The receiver could also be
adapted to alternately turn on two

relays, one for forward, one for reverse,
by using the second section of the 4013
dual flipflop, IC3.

Playmaster 60/60
blows output transistors

I would appreciate any help you
could give me regarding a problem I
have had with the Playmaster 60/60 am-
plifier.

In the past fifteen years I have ser-
viced (as a hobby) many amplifiers and
have built twelve complete stereos. The
Playmaster 60/60 is the first kit set I
have built, the previous ones being
completely from scratch. In other
words, I am not inexperienced but this
problem with the Playmaster has me
beat.

I bought the kit from Altronics in
August of last year. Construction went
smoothly and the pre-operational check
went according to the magazine article.
After two hours of use one pair of
MJ55003/MJ5004 transistors _ blew.
Everything was checked and the transis-
tors replaced but the same thing hap-
pened again, this time in the opposite
channel.

I read the errata about changing to
the MJ340 transistor for improved ther-
mal tracking. After doing this the exact
problem recurred two more times. At
one stage, four of the 10 1W resistors
stopped working.

As a last resort I mounted the four
power output transistors on the bottom
of the chassis for maximum heatsinking
but this time the MJ5003/MJ5004 pair
blew after only ten minutes. As before,
everything had been checked prior to
switch-on, especially using the 1000
resistors to set the quiescent current.

As you can see this is starting to cost
me a lot of money so I don’t want to
work on it anymore unless you have
some idea as to what the problem could
be. At all times, the voltages have been
exactly as specified in the circuit dia-
gram. After each “blow-up” the heat-
sink has been too hot to touch. (R.W.
Lake Grace, WA).

@ The problem with thermal runaway
appears to be caused by instability.
First, check the value of the 68pF com-
pensation capacitors between base and
collector of Q11 in both channels. This
should read 68p. At least one kit sup-
plier has incorrectly supplied 0.68pF ca-
pacitors which read p68. The transistor
heatsink should also be earthed. Both
these problems were covered in the arti-
cle entitled “Feedback on the Playmas-
ter 60/60 stereo amplifier” published in
the May 1987 issue of EA. @

ELECTRONICS Australia, June 1987 127

HF yi a

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398 5005

VINTAGE B & W TV: Bush Simpson
3-17” & 2-21” plus service manual, $50.
557 6692.

INTO RS232/DB-25 INTERFACING?
Save money and make your own mini-
testers, break out boxes, 2 way gender
benders, etc. Plated through boards $4
each, 4 way gender bender boards $14,
256K printer buffer short form kits from
$39, computer & printer switches $12,
serial board for buffer $18. For more
info. Send SAE to Don McKenzie, 29
Ellesmere Cres., Tullamarine 3043.

AMIDON FERROMAGNETIC CORES:
Large range for all receiver and trans-
mitter applications. For data and price
list and 105X220 SASE to: R. J. & U.
S. Imports, P.O. Box 157, Mortdale,
N.S.W. 2223. Close during June.
N.S.W.: Geoff Wood Electronics, Lane
Cove. Webb Electronics, Albury. A.C.T.:
Electronic Components, Fyshwick
Plaza. Vic.: Truscott Electronics, Croy-
don. W.A.: Willis Trading Co., Perth.

DO YOU WANT TO BE A RADIO
AMATEUR?

The Wireless Institute of Australia,
established in 1910 to further the
interests of Amateur Radio. conducts a
Correspondence Course for the A.O.C P
and L.A.O.C.P. Examinations conducted
by the Department of Communications
Throughout the Course, your papers are
checked and commented upon to lead
you to a successful conclusion

For further information, write to

THE COURSE SUPERVISOR ——
W.LA. (N.S.W. DIVISION) (=)

P.O. Box 1066
PARRAMATTA, N.S.W. 2150.

RCS. Rawi10 Pry. Lar.

Established 1933
IS THE ONLY COMPANY
WHICH MANUFACTURES AND
SELLS EVERY PCB & FRONT PANEL

published in EA and ETI
651 Forest Road Bexley 2207
AUSTRALIA
RING (02) 587 3491 FOR INSTANT PRICES
24-HOUR TURNAROUND SERVICE

ELECTRONIC ASSEMBLY
Quality hand assembly of PCBs
Component sourcing & Production consultation
Complete manufacturing service
Economic rates — Let us give you a quote

M.B.M. ENTERPRISES
25 Abbott St. Mendooran 2842
(068) 48 8140

RECORDING STREE LenTiW j 1

Ni

music SOUND

GENERATE ELECTRICITY
FROM THE SUN
ARCO PV PANELS

M55B 53 WATTS 12V
M75B 47 WATTS 12V
Provide power for pumping, lighting and
refrigeration. Now only $8/WATT.

ELANTE PTY LTD
382 CANTERBURY RD.
SURREY HILLS, 3127
Ph: (03) 836-9966

ACE RADIO (02) 949 4871

Manufacturers & Enthusiasts

Do you have problems sourcing
semiconductor devices at reasonable
prices?

If so contact us regarding your
requirements
10B/3 Kenneth Rd,
Manly Vale 2093

A NEW CONCEPT FOR LOW VOLTAGE PROJECTS
COPPER FOIL TAPE: thin pure copper tape backed
by special hi-tack adhesive. Current carrying capacity, 5
amps, FULLY TESTED at 24V 5A. Not recommended for
mains voltage.

4mm...RRP $8.03 6mm...RRP $9.84

GIFFORD PRODUCTIONS
PO Box 62, St Kilda, Vic 3182. (02) 534 3462

33 metre rolls

Letters to the Editor
- cld from page 5

the unbroken power supply.

Solid state logic continuously checks
the voltage and frequency of the mains,
switching over instantly the moment any
anomaly is detected. The result is a con-
tinuous sinusoid of constant frequency
and amplitude, making the Exide
Powerguard a true “‘no-break UPS”.

We hope that by publishing this you
will correct any mistaken impression
that any of your readers might have
formed from your feature.

The fact is, the Exide Powerguard
represents a successful departure from
off-line UPS performance, providing a

low cost source of conditioned and
standby power tailored to the realities
of computer and similar systems.

B. Donaldson,

National Marketing Manager,

Pacific Dunlop Batteries — Industri-
al.

(Previously Chloride Batteries Aus-
tralia Ltd).

Congratulations on
metric time

I heartily congratulate the Australian
Government on introducing Metric
Time. I believe that it is well overdue.

Almost everything has gone metric
except time — up ‘till now! Once the
rest of Australia converts to metric

time, Sir Joh will feel that he has made
the wrong decision and then Queens-
land will convert as well.

The Government has kept the secret
very well, thereby stopping the com-
munity revolt, although the timing of
the announcement wasn’t the best
(April 1st).

Congratulations are also in order to
you and Dick Smith for the design of
the first Digital Metric Clock. Convert-
ing to metric time may take a while, but
with your helpful article and the metric
clock project, it will take no time at all
(pun pun!).

Good on you EA for producing yet
another useful (useless?) project.

S. Schulz,

Bayswater, Vic.

PS: Happy April Fools’ Day!

Car Burglar Alarm ... ctd from page 63

tioned 10-15cm apart and facing towards
each other.

Whatever arrangement you use, make
sure that the environment in the vicinity
of the transducers is perfectly still. This
is to ensure that the signal picked up by
the receiver remains constant.

Initially, the sensitivity control (VR1)
should be set to minimum; ie, fully anti-
clockwise (not clockwise as incorrectly
stated in the April issue). It’s then a
matter of carefully adjusting VR2 for
maximum waveform amplitude at pin 9
of IC1b as shown on a CRO.

If you don’t have a CRO, adjust VR2
for maximum DC voltage across C6.

One problem that’s likely to be en-
countered here is that the metal adjust-
ment tab of the trimpot makes the unit
sensitive to the presence of the screw-

driver. For this reason, it’s best to use a
plastic tool to adjust VR2.

Once VR2 has been correctly adjust-
ed, it’s simply a matter of adjusting
VR1 to give the required sensitivity.

Note that twin core shielded cable
must be used to connect the transmitter
if it is wired in maximum drive configu-
ration (ie, connected between pins 2
and 4 of IC2). The braid of the cable
should be connected to the earth pad on
the PCB between the two transmitter
terminals. Fig.3a shows the details.

Note: the wiring diagram in the April
issue incorrectly shows the use of single
core shielded cable for the maximum
drive configuration. This results in
greatly reduced sensitivity.

Single core cable should only be used
when the transmitter is wired in mini-

mum drive configuration as shown in
Fig.3b. This should provide adequate
sensitivity for most situations, including
car burglar alarms.

Another problem with the ultrasonic
alarm can occur if the transducers are
soldered directly to PC pins on the
PCB. In this case, mechanical noise
generated when the relay turns off can
cause repeated false triggering, particu-
larly at high sensitivity settings.

This problem can easily be solved by
isolating the transducers from the PCB.
Alternatively, the relay can be quiet-
ened by sticking a small piece of tape to
the end of the relay armature and by
bending the two outer relay contacts to-
wards each other to reduce the travel of
the changeover contact.

Finally, readers should note that the
C and N/C terminals were shown trans-
posed on the wiring diagram on page 47
of the April issue. FA)

BELTS BELTS BE LTS BELTS BELT
TS BELTS Eco BELTS BELTS BE
BELTS BELTS BE LTS BELTS BELT

TS BELTS BEL GAUDIOEDRIVE ia "TURNTABLE BELTS Cit "PINCHROLLERS L¥6 MIDEO3 BELTSELTS BELTSBE

TURNTABLES
Turntable belts are available in

5mm & 6mm with diameters
cowiencing from 122 mm up to

292m
TRADE FEM WHOLESALE ENQUIRIES WELCOME

Imported & Distributed by WES COMPONENTS PTY. LTD.
For a comprehensive catalogue send your company of
business: details to: PO. Box 451 Ashfield NSW 2131 Aust.,

Phone: (02) 797 9866 Fax: (02) 799 7051

VIDEO

Over 60 Video Belt Kits in stock to
suit most popular video machines.
Other video parts also available ie:
pinchrollers, heads, etc.

WAGNER ELECTRONIC SERVICES PTY. LTD.,

305 Liverpool Rd., Ashfield, N.SW. 2131. Aust.,
Phone: (02) 798-9233

AUDIO CASSETTE

A range of belts is available in
1.2mm square & 1.4mm square,
from the 19mm diameter up to
136 mm diameter. These will suit
most audio products. If a flat belt is
required our range includes 3 mm,
4mm, 5mm & 6mm belts in an
assortment of lengths. An
assortment of pinchrollers is also
available.

Please call for a stocklist or bring in your
sample belt and we will match it.

WAGNER

Add

Next month in

Headphone amplifier and
phase corrector for CD players

CD players which have only one D-A converter inevitably have a phase differ-
ence between channels. This unit corrects that error and also provides two head-
phone outputs with adjustable level. The very high quality circuit does not de-
grade the CD signal quality.

The romance of railways

We begin a new series of articles on railways, starting with steam locomotives
and progressing to electric and diesel-electric locos. Written by the author of
‘Op amps explained”, it is certain to be an erudite overview.

X-wing helicopters

Read about the development of high speed helicopters which will have rigid
rotors and which will even include an emergency exit system.

"Note: although these articles have been prepared for publication, circumstances may change the final content.

Electronics Australia Reader Service

“Electronics Australia” provides the following services: problems by telephone.

BACK ISSUES: available only until stocks are exhausted. OTHER QUERIES: technical queries outside the scope of
Price: $4.00 “Replies by Post’, or submitted without fee, may be
PHOTOSTAT COPIES: when back issues are exhausted, answered in the “information Centre" pages at the discre-
photocopies of articles can be supplied. Price: $4 per pro- tion of the Editor.

ject or $8 where a project spreads over several issues. PAYMENT: must be negotiable in Australia and made pay-
PCB PATTERNS: high contrast. actual size transparencies able to “Electronics Australia”. Send cheque, money order
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130 ELECTRONICS Australia, June 1987

ADVERTISING
INDEX

Ace Radio. ...........:::esccccccereneeees 128
ACHIONICS 0.........ceseeseesseeeeeesenes 128
Ad@al:. cciiccnavatchensrn th acre 50
Allen Bradley ..........:ccesseseeeees 50
AItrONICS o.......eceeeeeeessentteeeeee 54-59
AIMIOX™ fciectipceicac iccdeastienaas 73
Aust Govt. Recruiting ...... 42,43,73
Chapman LE. ........ ees 125
Control Data woo. cccceeeseeeeees 18
(1 (01 (0 | - a ere 18
David Reid oo... ceeeeeneees 37
Diamond Systems_ .............666 121
Dick Smith Electronics. ....... 9,75-82
DNA Communications ........... 117
Elante:: ccceeset teats 128
ElWiStroniCS .........ccccsesseeecseeseees 70
EIM@ ASCO .....ecceececceessteeeeeseeeee IBC
EMtronics ..........ccccccsseseeecneeenees 62
Fairchild ......cccccceeeseeeneees 14,15
Federal Publishing 98,108,110,111
Geoff WOOd ee ciiseescccceesenees 40
Gifford Productions ..........0000 128
CS ta iicitee Giatehs ttt. 95
NI: \\ (or: | 30-35
KalextronicS ........ccceccseeees 123
Macro Dynamics ............006 119
MBM Enterprises. .............0066 128
Microbee_ .........:.:cccceeseeees 102,103
Micro Education ...............0008 128
PIUIDS: ct eiieiecietoeees ta thans IFC
RCS Radio .......ecccceeceseeeseee 128
Rifas eter ccteteha tinh stunes ats OBC
RitrOnicS oo... ceeeceeseseeseeees 20-25
Scan Audio .......cccceceeeeeeseeees 107
Selectronic Components ........... 85
SEMIKION ooo... ceeeeeecseeeeeseseeneees 92
SEMNEC: oc. cmioiiieemniren 29
Sheridan Electronics ............ 66,67
ho] (0) ¢ Caan ee 86
Texas Instruments. ............... 90,91
University of NSW ou... 107
VAM TOSt: cei ciaisenderssiatacnecsenede 85
VidGOSAal ieteai steve eles 122
VObi sesh h asishevecets nt semenss 49
WES: se. sietidncduviotenteniiaiwetrdens 128
Westinghouse Systems. .......... 124
WIA. veocctnsuticttditnninva estore: 128

How to beat the high cost
of cheap meters.

You get what you pay for.
So get the Fluke 70 Series.

You'll get more meter for your money,
whether you choose the affordable 73,
the feature-packed 75 or the deluxe 77.

All of them will give you years of
performance, long after cheaper meters
have pegged their fishhook needles for
the last time.

That's because they're built to last, in-
side and out. So they're tough to break. They
don’t blow fuses all the time. You don’t
even have to replace batteries as often.

And they'e backed by a 3-year warranty.
Not the usual 1-year.

Of course, you may only care that the
world-champion 70 Series combines digital
and analog displays with more automatic
features, greater accuracy and easier opera-
- tion than any other meters in their class.

‘3 You may not care that they have a lower
overall cost of ownership than all the other
“bargain” meters out there.

But just in case, now you know.

FROM THE WORLD LEADER
IN DIGITAL MULTIMETERS.

FLUKE 73 FLUKE 75 FLUKE 77
Analog/digital display Analog/digital display__ Analog/digital display

Volts, ohms, 10A, diode Volts, ohms, 10A. mA, —_-Volts, ohms, 10A, mA

Sle. ees test diode test diode test
2 a me = = aS = Autorange Audible continuity Audible continuity

0.7% basic de accuracy Autorange/range hold_ “Touch Hold" function

E, YB Mf KE ‘A AY CoO 2000+ hour battery life 0.5% basic dc accuracy Autorange/range hold
Se ee ee 3-year warranty 2000+ hour battery life 0.3% basic de accuracy

a

Instruments Pty. Ltd. 3-year warranty zat ar ty life
-year warranty

Talk to your local Elmeasco distributor about Fluke —
e A.C.T. John Pope Electrical (062) 80 6576 ¢ J Blackwood & Sons (062) 80 5235 ¢ George Brown (062) 80 4355

© N.S.W. Ames Agency 699 4524 e¢ J Blackwood & Sons ¢ George Brown 519 5855 Newcastle 69 6399 © Bryan Catt Industries 526 2222 ¢D.G.E. Systems (049) 69 1625
© Petro-Ject 550 1388 ¢ David Reid 267 1385 ¢ W. F. Dixon (049) 61 5628 ¢ Macelec (042) 29 1455 e Ebson 707 2111 ¢ Selectroparts 708 3244 © Geoff Wood 427 1€76

e@ N. TERRITORY J Blackwood & Son (089) 84 4255, 52 1788 « Thew & McCann (089) 84 4999

© QUEENSLAND Auslec ¢ Petro-Ject (075) 91 4199 ¢ St Lucia Electronics 52 7466 ¢ Cliff Electronics 341 4655 ¢ L. E. Boughen 369 1277 ¢ Fred Hoe & Sons 277 4311
@ The Electronic Shop (075) 32 3632 ¢ Thompson Instruments (Cairns) (070) 51 2404

e@ S. AUSTRALIA Protronics 212 3111 © Trio Electrix 212 6235 @ Industrial Pyrometers 352 3688 ¢ J Blackwood & Son 46 0391 © Petro-Ject 363 1353
© TASMANIA George Harvey (003) 31 6533 (002) 34 2233

© VICTORIA Radio Parts 329 7888 ¢ George Brown Electronics Group 878 8111 ¢ G B Telespares 328 4301 ¢ A.W.M. Electrical V/holesalers @ Petro-Ject 419 9377
e J Blackwood & Sons 542 4321 ¢ R.K.B. Agency 29 7336 ¢ Sirs Sales (052) 78 1251 ® Mektronics Co 690 4593 e Truscott Electronics 723 3094

e W. AUSTRALIA Atkins Carlyle 481 1233 ¢ Dobbie Instruments 276 8888 ¢ Protronics 362 1044

wan CMOS PRODUCTS LIST

TOTAL | ORGANIZATION ACCESS POWER STANDBY POWER OPERATING DATA RETENTION
BIT | (WOE TYP. (MAX) TYP (MAX) CURRENT

PRODUCT RD x BIT) TIME(n8)

AKM6264ALSP
ALFP.

‘AKM6287P
cG

‘AKM622561P
LP

AKM62256LP-S_— |
CFP-S

RIFA

MELBOURNE (03) 487 3333
SYDNEY (02) 858 5966
ADELAIDE (08) 232 0001
BRISBANE § = (07) 277 4311

PERTH (09) 367 6330
HOBART (002) 342 233
LAUNCESTON (003) 316 533

R

Asahi Kasei Microsystems was formed froma
joint venture between AMI of the United States
and Asahi Chemical of Japan. A design centre
was opened for design and marketing of
custom and application specific LSI’s based
on AMI technology. Asahi Kasei Microsystems
has entered a co-operative relationship with
Hitachi Ltd. for the acquisition of its advanced
CMOS process technology.